He will join the internet search engine in three months in the newly created post of head of comms for UK, Ireland and Benelux.
Collins handed in his notice last week. He will oversee Google's media strategy and report to Rachel Whetstone, director of comms and public affairs, EMEA.
WS is hunting a head of public affairs, who will report to MD of corporate and PA Michael Prescott.
WS UK & Ireland chief executive Colin Byrne said: 'I am working with Coke on the evolution of our broad-based team and we are looking at strengthening the team both from inside and outside.' The agency secured the coveted account at the end of 2004.
Byrne added that Collins had been a 'terrific colleague' and that he was joining a 'terrific brand'.
Collins joined WS in October 2004 from the Department for Education and Skills, where he was head of news and strategic planning. Before that he was head of comms at the Amalgamated Engineering and Electrical Union (now Amicus).
Google recruited Whetstone, previously chief-of-staff to ex-Conservative leader Michael Howard, late last year (PRWeek, 18 November 2005).
The firm has since brought in a triumvirate of agencies: Portland PR for corporate, Octopus Communications for trade media and Cow PR for consumer.
Collins joins as Google continues to extend its tentacles outside its web search offering. Last month it announced it would provide financial news and quotes.
This week the internet search icon launched a competition inviting schoolchildren to create an image representing life in the UK. Winners of the 'Doodle 4 Google' contest will have their creations displayed on the company's famously sparse UK homepage.