Cain will be primarily responsible for the strategic consultancy on Castrol's sponsorship of the Fifa World Cup, which has been awarded to Mindshare after a competitive pitch against undisclosed agencies.
Castrol is an official sponsor of the Fifa World Cup 2010 in South Africa and 2014 in Brazil.
Castrol's global brand director, Des Johnson, said: "Mindshare's team demonstrated a real strategic grasp of how we might use football to build our brand across the globe.
"They are now working with our central sponsorship team and markets worldwide to deliver that strategy. Simply put, they get brands and they get football. Stuart Cain is a great signing to a strong team."
As well as working on Castrol, Cain will spend time developing Mindshare's burgeoning sports and entertainment business working with Sean Jefferson, who heads Mindshare's Invention Group.
Prior to his tenure as commercial head at Glasgow Rangers, Cain was director of sales and marketing at Coca Coal Championship side Wolverhampton Wanderers Football Club and was previously director of media at Molson Coors Brewers.
At Coors he was responsible for the Carling brand's sponsorship of the Premier League and took strategic responsibility for all sponsorship, media planning and buying, direct marketing and online activity at the brewer -- including the award-winning Carling brand sponsorship of the Premier League and its impressive music sponsorship portfolio, such as the Carling Weekend Reading and Leeds Festivals and a range of content-based music programmes.
Jefferson said: "This is an outstanding hire. Rare is it for someone to have such strong sports marketing, music, content and media expertise, on both the client and rights owner sides."