Pearman will leave Birds Eye at the start of the month to become marketing director for Europe, Middle East and Africa for General Mills, which is behind big brands such as Häagen-Dazs and Yoplait.
Birds Eye said it was working to ensure a smooth transition following his departure and that it hoped to announce a successor shortly.
Pearman joined Birds Eye from Heinz in January 2008, replacing Andy Beattie as marketing director. Prior to his commercial director role at Heinz, he was European brand manager for Wall's Magnum where he launched Magnum 7 Sins, the brand's most successful initiative.
During his early career, he held various brand manager positions at both Unilever and Nestlé.
"I would like to take this opportunity to thank Ben for his contribution to the Birds Eye business his infectious enthusiasm, passion for the Birds Eye brand and leadership of his team and our valued external partners are greatly appreciated," said Birds Eye UK and Ireland managing director Anne Murphy. "We wish him and his family our very best wishes for their move to Switzerland."
Parent company Birds Eye Iglo acquired Italian frozen foods business Findus Italy from Unilever in July for £681m.
The deal is part of CEO Martin Glenn's plans to expand its business and double European sales over the next three years.