Bremen striker Almeida joins Besiktas
Portugal international Almeida's contract with Werder was running out at the end of the season and the Germans opted to sell the 26-year-old now to cash in on a transfer fee.
"A contract extension was not possible. Receiving a fee through his transfer was the best option for Werder," club managing director Klaus Allofs told the Bremen website.
There were no details available on the length of his new deal or the amount of the fee.
Almeida joined from Porto in 2006 and scored 41 goals in 117 league games for Werder. He is also the club's top scorer this season with nine goals in 17 games.