Boomlagoon will produce "convivial and intriguing games" for mobile and web platforms, starting with HTML5 titles.
Stén was Rovio's lead server architect, while Erikoinen was lead artist on Angry Birds. The former has been named as chief executive officer of the new studio, with the latter serving as chief creative officer.
"We know a thing or two about successful games and high volumes, and we'll use this knowledge to spawn something very cool and new," Stén told Venture Beat.
"If we play our cards right, we just might end up with the next Angry Birds."
Angry Birds has been downloaded more than 12 millions times across multiple platforms. The latest entry in the series, Angry Birds Space, was released in March.
> 'The Simpsons' rumoured for 'Angry Birds Space' level
Watch a trailer for Angry Birds Space below: