Pizarro spent last season on loan at Bremen from Chelsea, scoring 17 Bundesliga goals during his spell.

The 31-year-old moved for an undisclosed fee after signing a three-year contract at Weserstadion.

"I am happy to be back as I wanted desperately to return to Werder," Pizarro said.

Piza joined Chelsea from Bayern Munich two seasons ago, but failed to impress at Stamford Bridge despite scoring on his debut against Birmingham City.