Document and Entity Information - USD ($)
$ in Billions
 12 Months Ended
Jan. 31, 2022
Mar. 24, 2022
Jul. 31, 2021
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Jan. 31, 2022    
Document Fiscal Year Focus 2022    
Document Fiscal Period Focus FY    
Trading Symbol AMBA    
Entity Registrant Name AMBARELLA, INC.    
Entity Central Index Key 0001280263    
Current Fiscal Year End Date --01-31    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Common Stock, Shares Outstanding   38,065,304  
Entity Public Float     $ 2.8
Entity File Number 001-35667    
Entity Tax Identification Number 98-0459628    
Entity Address, Address Line One 3101 Jay Street    
Entity Address, City or Town Santa Clara    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 95054    
City Area Code 408    
Local Phone Number 734-8888    
Entity Incorporation, State or Country Code E9    
Title of 12(b) Security Ordinary Shares, $0.00045 Par Value Per Share    
Security Exchange Name NASDAQ    
Entity Interactive Data Current Yes    
Document Annual Report true    
Document Transition Report false    
Auditor Name PricewaterhouseCoopers LLP    
Auditor Location San Jose, California    
Auditor Firm ID 238    
Documents Incorporated by Reference

Certain information is incorporated into Part III of this report by reference to the Proxy Statement for the Registrant’s annual meeting of shareholders to be held on or about June 7, 2022 to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K.