Onto Innovation (ONTO) 10-K 2021 FY Annual report

Exhibit 31.1

Rule 13a-14(a) Certification of Chief Executive Officer
Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

I, Michael P. Plisinski, certify that:

1. I have reviewed this annual report on Form 10-K of Onto Innovation Inc.;

2. Basedonmyknowledge,thisreportdoesnotcontainanyuntruestatementofamaterialfactoromittostateamaterial fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by thisreport;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in thisreport;

4. Theregistrant’sothercertifyingofficerandIareresponsibleforestablishingandmaintainingdisclosurecontrols and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant andhave:

a.Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is beingprepared;

b.Designedsuchinternal control over financial reporting, or caused suchinternal control over financialreporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reportingandthepreparationoffinancialstatementsforexternalpurposesinaccordancewithgenerallyaccepted accountingprinciples;

c.Evaluatedtheeffectivenessoftheregistrant’sdisclosurecontrolsandproceduresandpresentedinthisreport our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation;and

d.Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting;and

5. Theregistrant’sothercertifyingofficerandIhavedisclosed,basedonourmostrecentevaluationofinternalcontrol overfinancialreporting,totheregistrant’sauditorsandtheauditcommitteeoftheregistrant’sboardofdirectors(or persons performing the equivalentfunctions):

a.Allsignificantdeficienciesandmaterialweaknessesinthedesignoroperationofinternalcontroloverfinancial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information;and

b.Anyfraud,whetherornotmaterial,thatinvolvesmanagementorotheremployeeswhohaveasignificantrole in the registrant’s internal control over financialreporting.

Date: February 25, 2022

By:	/s/ Michael P. Plisinski
	Michael P. Plisinski
	Chief Executive Officer