The Switzerland international is ecstatic about taking on a new challenge with the Hessian outfit this season, after S04's new arrivals reduced his chances of a starting place.
The arrivals of Kevin-Prince Boateng and Christian Clemens have lowered Barnetta's chances of making regular appearances at Veltins Arena.
The Swiss winger is now relishing the opportunity of making an impact with Armin Veh's side this season, with the team having recently qualified for the Europa League group stages.
"I'm delighted that the deal went through and about getting to know the city and the team," the 28-year-old was quoted as saying on the club's official website.
"First, I must meet with the national team, however, and will return to Frankfurt with Pirmin Schwegler in 10 days."
Barnetta scored 10 goals during 68 appearances for his country to date.