Besiktas have followed up the signing of Simao by swooping for his international team-mate Hugo Almeida.
Werder Bremen were unable to meet the Portugal striker's wage demands and Besiktas stepped in to sign the 26-year-old for a fee of 2million euros (£1.7m).
Almeida, who has scored 11 goals in 20 games for Werder this season, has signed a three-year contract with the Turkish outfit.
After initially joining Werder on loan in 2006, the former Porto striker has scored a total of 63 goals in 176 games for the Bundesliga side while racking up 12 goals in 33 international appearances for Portugal.
Almeida follows compatriot Simao in signing for Besiktas, who are currently way off the pace in the Turkish championship as they lie fifth, 14 points adrift of leaders Trabzonspor after 17 matches.
Simao signed a two-and-a-half year deal with the 13-time Turkish champions on Wednesday after they agreed a 7m euro fee (£6m) with Atletico Madrid for the 31-year-old winger.