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

September 4, 2012

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:

On September 4, 2012, ON Semiconductor Corporation (“Company”) closed an exchange offer with certain holders (“Holders”) of its 2.625% Convertible Senior Subordinated Notes Due 2026 (“Old Notes”) pursuant to the terms of its previously announced, privately negotiated exchange agreements (“Exchange Agreements”) with the Holders. Pursuant to the terms of the Exchange Agreements, the Holders exchanged an aggregate of $99,878,000 principal amount of the Old Notes held by the Holders for an equal aggregate principal amount of the Company’s new 2.625% Convertible Senior Subordinated Notes Due 2026, Series B (“New Notes”) and cash consideration. The New Notes: (i) were issued beginning on September 4, 2012; (ii) form part of the same series with the Company’s 2.625% Convertible Senior Subordinated Notes Due 2026, Series B issued in December 2011; and (iii) are an additional issuance under the indenture dated as of December 15, 2011, by and among the Company, Deutsche Bank Trust Company Americas, as trustee, and the subsidiary guarantors (“Subsidiary Guarantors”) listed therein (“Indenture”).

The terms of the Indenture and the New Notes are described in the Company’s Current Report on Form 8-K, filed with the Securities and Exchange Commission (“Commission”) on August 23, 2012, which is incorporated by reference herein. The New Notes can be accelerated upon the occurrence of customary events of default, generally including the Company’s failure to comply with its obligations in the Indenture, in certain cases, after a grace period. However, the New Notes are subordinated in right of payment, to the extent and in the manner provided in the Indenture, to the prior payment of senior indebtedness of the Company and the Subsidiary Guarantors. Deutsche Bank Trust Company Americas and its affiliates may provide banking, investment and other services to us and our affiliates from time to time. The description of the Indenture is qualified in its entirety by reference to the complete text of the Indenture, a copy of which was filed as Exhibit 4.1 to the Company’s Current Report on Form 8-K filed with the Commission on December 19, 2011 and is incorporated herein by reference.

The disclosure set forth in Item 2.03 of this Current Report on Form 8-K is incorporated herein by reference. The disclosure under this Item 3.02 and the terms of the Indenture and the New Notes described in the Company’s Current Report on Form 8-K, filed with the Commission on August 23, 2012, is also incorporated by reference herein.

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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 hereunto duly authorized.

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EXHIBIT INDEX

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