Exhibit 99.1

ON Semiconductor Reports First Quarter 2021 Results

PHOENIX, Ariz. – May 3, 2021 – ON Semiconductor Corporation (Nasdaq: ON) today announced results for the first quarter of 2021 with following highlights:

“We delivered strong results driven by disciplined execution in a strong demand environment across our focus end-markets. Our gross margin initiatives are beginning to show early results with first quarter gross margin expanding by 80 basis points quarter-over-quarter. We remain confident in our ability to further expand our margins as we continue to make structural changes to the business,” said Hassane El-Khoury, president and CEO of ON Semiconductor.

“The momentum in our strategic automotive and industrial end-markets is accelerating. During the first quarter, we secured key platform design wins for our Silicon Carbide and Silicon based power products, further solidifying our market leadership in vehicle electrification.”

Selected financial results for the quarter are shown below with comparable periods:

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Revenue Summary

($ in millions)

(Unaudited)

SECOND QUARTER 2021 OUTLOOK

The following table outlines ON Semiconductor’s projected second quarter of 2021 GAAP and non-GAAP outlook.

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TELECONFERENCE

ON Semiconductor will host a conference call for the financial community at 9 a.m. Eastern Daylight Time (EDT) on May 3,2021 to discuss this announcement and ON Semiconductor’s 2021 first quarter results. The Company will also provide a real-time audio webcast of the teleconference on the Investor Relations page of its website at http://www.onsemi.com. The webcast replay will be available at this site approximately one hour following the live broadcast and will continue to be available for approximately 30 days following the conference call. Investors and interested parties can also access the conference call via telephone by dialing (833) 303-2043 (U.S./Canada) or: (236) 714-3942 (International). In order to join this conference call, you will be required to provide the Conference ID Number – which is 5398970.

About ON Semiconductor

ON Semiconductor (Nasdaq: ON) is driving energy efficient electronics innovations that help make the world greener, safer, inclusive and connected. The company has transformed into our customers’ supplier of choice for power, analog, sensor and connectivity solutions. The company’s superior products help engineers solve their most unique design challenges in automotive, industrial, cloud power, and Internet of Things (IoT) applications. For more information, visit http://www.onsemi.com.

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ON Semiconductor and the ON Semiconductor logo are registered trademarks of Semiconductor Components Industries, LLC. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. Although the Company references its website in this news release, information on the website is not to be incorporated herein.

This document includes “forward-looking statements,” as that term is defined in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements, other than statements of historical facts, included or incorporated in this document could be deemed forward-looking statements, particularly statements about the future financial performance of ON Semiconductor, including financial guidance for the year ending December 31, 2021. Forward-looking statements are often characterized by the use of words such as “believes,” “estimates,” “expects,” “projects,” “may,” “will,” “intends,” “plans” or “anticipates” or by discussions of strategy, plans or intentions. All forward-looking statements in this document are made based on our current expectations, forecasts, estimates and assumptions and involve risks, uncertainties and other factors that could cause results or events to differ materially from those expressed in the forward-looking statements. Additional factors that could affect our future results or events are described under Part I, Item 1A “Risk Factors” in our 2020 Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on February 16, 2021 (our “2020 Form 10-K”) and from time to time in our other SEC reports. Readers are cautioned not to place undue reliance on forward-looking statements. We assume no obligation to update such information, except as may be required by law. You should carefully consider the trends, risks and uncertainties described in this document, our 2020 Form 10-K and other reports filed with or furnished to the SEC before making any investment decision with respect to our securities. If any of these trends, risks or uncertainties actually occurs or continues, our business, financial condition or operating results could be materially adversely affected, the trading prices of our securities could decline, and you could lose all or part of your investment. All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by this cautionary statement.

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ON SEMICONDUCTOR CORPORATION

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS

(in millions, except per share data)

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ON SEMICONDUCTOR CORPORATION

UNAUDITED CONSOLIDATED BALANCE SHEETS

(in millions)

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ON SEMICONDUCTOR CORPORATION

UNAUDITED RECONCILIATION OF NET INCOME (LOSS) TO ADJUSTED EBITDA AND

NET CASH PROVIDED BY OPERATING ACTIVITIES

(in millions)

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ON SEMICONDUCTOR CORPORATION

UNAUDITED RECONCILIATION OF NET INCOME (LOSS) TO ADJUSTED EBITDA AND

NET CASH PROVIDED BY OPERATING ACTIVITIES (Continued)

(in millions)

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ON SEMICONDUCTOR CORPORATION

RECONCILIATION OF GAAP VERSUS NON-GAAP DISCLOSURES

(in millions, except per share and percentage data)

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ON SEMICONDUCTOR CORPORATION

RECONCILIATION OF GAAP VERSUS NON-GAAP DISCLOSURES (Continued)

(in millions, except per share and percentage data)

Certain of the amounts in the above tables may not total due to rounding of individual amounts.

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ON SEMICONDUCTOR CORPORATION

RECONCILIATION OF GAAP VERSUS NON-GAAP DISCLOSURES (Continued)

(in millions, except per share and percentage data)

Total share-based compensation related to the Company’s restricted stock units, stock grant awards and employee stock purchase plan is included below:

SUPPLEMENTAL FINANCIAL DATA

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NON-GAAP MEASURES

To supplement the consolidated financial results prepared in accordance with GAAP, ON Semiconductor uses certain non-GAAP measures, which are adjusted from the most directly comparable GAAP measures to exclude items related to the amortization of intangible assets, amortization of acquisition-related intangibles, expensing of appraised inventory fair market value step-up, inventory valuation adjustments, purchased in-process research and development expenses, restructuring, asset impairments and other, net, goodwill impairment charges, gains and losses on debt prepayment, non-cash interest expense, actuarial (gains) losses on pension plans and other pension benefits, third party acquisition and divestiture related costs, tax impact of these items and certain other non-recurring items, as necessary. Management does not consider the effects of these items in evaluating the core operational activities of ON Semiconductor. Management uses these non-GAAP measures internally to make strategic decisions, forecast future results and evaluate ON Semiconductor’s current performance. In addition, the Company believes that most analysts covering ON Semiconductor use the non-GAAP measures to evaluate ON Semiconductor’s performance. Given management’s and other relevant use of these non-GAAP measures, ON Semiconductor believes these measures are important to investors in understanding ON Semiconductor’s current and future operating results as seen through the eyes of management. In addition, management believes these non-GAAP measures are useful to investors in enabling them to better assess changes in ON Semiconductor’s core business across different time periods. These non-GAAP measures are not prepared in accordance with, and should not be considered alternatives or necessarily superior to, GAAP financial data and may be different from non-GAAP measures used by other companies. Because non-GAAP financial measures are not standardized, it may not be possible to compare these financial measures with other companies’ non-GAAP financial measures, even if they have similar names.

Adjusted EBITDA

Adjusted EBITDA is a non-GAAP financial measure that represents net income before interest expense, interest income, provision for income taxes, depreciation and amortization expense and special items. We use the adjusted EBITDA measure for internal managerial evaluation purposes, as a means to evaluate period-to-period comparisons and as a performance metric for the vesting and release of certain of our performance-based equity awards. SEC Regulation G and other federal securities laws regulate the use of financial measures that are not prepared in accordance with GAAP. We believe this measure provides important supplemental information to investors. However, we do not, and you should not, rely on non-GAAP financial measures alone as measures of our performance.

Non-GAAP Revenue

The use of non-GAAP revenue allows management to evaluate, among other things, the revenue from the Company’s core businesses and trends across different reporting periods on a consistent basis, independent of special items. In addition, non-GAAP revenue is an important component of management’s internal performance measurement and incentive and reward process as it is used to assess the current and historical financial results of the business and for strategic decision making, preparing budgets, obtaining targets and forecasting future results. Management presents this non-GAAP financial measure to enable investors and analysts to evaluate the Company’s revenue generation performance relative to the direct costs of operations of ON Semiconductor’s core businesses.

Non-GAAP Gross Profit and Gross Margin

The use of non-GAAP gross profit and gross margin allows management to evaluate, among other things, the gross margin and gross profit of the Company’s core businesses and trends across different reporting periods on a consistent basis, independent of non-cash items including, generally speaking, expensing of appraised inventory fair market value step-up and the impact from the change in revenue recognition on distributor sales. In addition, it is an important component of management’s internal performance measurement and incentive and reward process as it is used to assess the current and historical financial results of the business and for strategic decision making, preparing budgets, obtaining targets and forecasting future results. Management presents this non-GAAP financial measure to enable investors and analysts to evaluate our revenue generation performance relative to the direct costs of revenue of ON Semiconductor’s core businesses.

Non-GAAP Operating Income and Operating Margin

The use of non-GAAP operating income and operating margin allows management to evaluate, among other things, the operating margin and operating income of the Company’s core businesses and trends across different reporting periods on a consistent basis, independent of non-cash items including, generally speaking, expensing of appraised inventory fair market value step-up, the impact from the change in revenue recognition on distributor sales, amortization and impairments of intangible assets, third party acquisition and divestiture related costs, restructuring charges and certain other special items as necessary. In addition, it is an important component of management’s internal performance measurement and incentive and reward process as it is used to assess the current and historical financial results of the business and for strategic decision

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NON-GAAP MEASURES (Continued)

making, preparing budgets, obtaining targets and forecasting future results. Management presents this non-GAAP financial measure to enable investors and analysts to evaluate the Company’s revenue generation performance relative to the direct costs of operations of ON Semiconductor’s core businesses.

Non-GAAP Net Income Attributable to ON Semiconductor and Non-GAAP Diluted Earnings Per Share

The use of non-GAAP net income attributable to ON Semiconductor and non-GAAP diluted earnings per share allows management to evaluate the operating results of ON Semiconductor’s core businesses and trends across different reporting periods on a consistent basis, independent of non-cash items including, generally, the amortization and impairments of intangible assets, expensing of appraised inventory fair market value step-up, the impact from the change in revenue recognition on distributor sales, restructuring, gains and losses on debt prepayment, non-cash interest expense, actuarial (gains) losses on pension plans and other pension benefits, third party acquisition and divestiture related costs, tax indemnification by third parties, tax impact of these items and other non-GAAP adjustments and certain other special items, as necessary. In addition, these items are important components of management’s internal performance measurement and incentive and reward process, as they are used to assess the current and historical financial results of the business and for strategic decision making, preparing budgets, setting targets and forecasting future results. Management presents these non-GAAP financial measures to enable investors and analysts to understand the results of operations of ON Semiconductor’s core businesses and, to the extent comparable, to compare our results of operations on a more consistent basis against those of other companies in our industry.

Free Cash Flow

The use of free cash flow allows management to evaluate, among other things, the ability of the Company to make interest or principal payments on its debt. Free cash flow is defined as the difference between cash flow from operating activities and capital expenditures disclosed under investing activities in the consolidated statement of cash flows. Free cash flow is not an alternate to cash flow from operating activities as a measure of liquidity. It is an important component of management’s internal performance measurement and incentive and reward process as it is used to assess the current and historical financial results of the business and for strategic decision making, preparing budgets, obtaining targets and forecasting future results. Management presents this non-GAAP financial measure to enable investors and analysts to evaluate our revenue generation performance relative to the direct costs of operations of ON Semiconductor’s core businesses.

Non-GAAP Diluted Share Count

The use of non-GAAP diluted share count allows management to evaluate, among other things, the potential dilution due to the outstanding stock options and restricted stock units excluding the dilution from the convertible notes that is covered by hedging activity up to a certain threshold. In periods when the quarterly average stock price per share exceeds $18.50, the non-GAAP diluted share count includes the anti-dilutive impact of the Company’s hedge transactions issued concurrently with the 1.00% convertible notes. As such, at an average stock price per share between $18.50 and $25.96, the hedging activity offsets the potentially dilutive effect of the 1.00% convertible notes. In periods when the quarterly average stock price per share exceeds $20.72, the non-GAAP diluted share count includes the anti-dilutive impact of the Company’s hedge transactions issued concurrently with the 1.625% convertible notes. As such, at an average stock price per share between $20.72 and $30.70, the hedging activity offsets the potentially dilutive effect of the 1.625% convertible notes.

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