UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D. C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

February 4, 2015

Date of report (Date of earliest event reported)

ON Semiconductor Corporation

(Exact name of registrant as specified in its charter)

(602) 244-6600

(Registrant’s telephone number, including area code)

Not applicable

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(a) – (d) Not applicable.

(e) First Half of 2015 Cash Bonus Program for Named Executive Officers — On February 4, 2015, the Compensation Committee (“Committee”) of the Board of Directors of ON Semiconductor Corporation (“Corporation”) determined specific bonus plan parameters for the Corporation’s semi-annual cash incentive program for the first half of 2015 (“Bonus Program”) for possible cash bonus awards to certain of our employees, including certain of our “named executive officers” identified in the Corporation’s 2014 annual meeting of stockholders proxy statement (the “2014 Proxy Statement”), namely: Keith D. Jackson, President and Chief Executive Officer; Bernard Gutmann, Executive Vice President and Chief Financial Officer and Treasurer; George H. Cave, Executive Vice President, General Counsel, Chief Compliance & Ethics Officer, Chief Risk Officer and Secretary; Robert A. Klosterboer, Executive Vice President and General Manager, Application Products Group; and Mamoon Rashid, Senior Vice President and General Manager, System Solutions Group. The Bonus Program was set up under the previously disclosed terms and conditions of the ON Semiconductor Corporation Amended and Restated Stock Incentive Plan (the “Plan”). The amount and payment of the actual award, if any, to each participant is in the discretion of the Committee.

Cash bonuses under the Bonus Program will be paid if the Corporation achieves a certain minimum non-GAAP earnings per share (the “Minimum Non-GAAP EPS”). Under the Bonus Program, the bonus pool is capped at 11% of non-GAAP net income. Non-GAAP earnings per share will be calculated by excluding certain items from GAAP net income, such as: gain (loss) on debt repurchase, debt exchange, early extinguishment of debt, etc.; restructuring, asset impairment and other charges, net; expensing of inventory fair market value step up; amortization of acquisition related intangible assets; non-cash interest expense; adjustment to reflect cash taxes; goodwill and intangible asset impairment; actuarial gains or losses on pension plans and other pension benefits; gains or losses on acquisitions; acquisition related costs; and extraordinary items.

Award opportunities for the first half of 2015 under the Bonus Program (expressed as a percentage of the officer’s base salary) for each of the named executive officers has the threshold, target, and stretch amount listed below. The Committee reviews these officer award opportunities from time-to-time.

(f) Not applicable.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

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