Whetstone will be based in London and report to California-based Google V-P of global comms and public affairs Elliot Schrage.
In the run-up to her appointment, which Google has previously denied, Whetstone was also linked with a return to former employer Tim Allan at Portland PR.
Allan denied any offer had been made but told PRWeek: 'The door was always open [for Whetstone to return].' She has also worked at Carlton Communications and was last month signed up as a contributor to Sky News's The Sky Report.
Google's IPO last year was an instant market success, prompting some analysts to predict its bubble might burst. Its growing list of ventures include news, maps and WiFi.
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