| Club: | Beşiktaş J.K. |
| Season: | 2008–09 |
| Manager: | Mustafa Denizli |
| Chairman: | Yıldırım Demirören |
| Chrtitle: | President |
| Mgrtitle: | Head coach |
| Stadium: | BJK İnönü Stadium |
| League: | Süper Lig |
| League Result: | 1st (13th title) |
| Cup1: | Turkish Cup |
| Cup1 Result: | Winners (8th title) |
| Cup2: | UEFA Cup |
| Cup2 Result: | First round |
| League Topscorer: | Bobô (12 goals) |
| Season Topscorer: | Bobô (20 goals) |
| Pattern La1: | _besiktas0809h |
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| Prevseason: | 2007–08 |
| Nextseason: | 2009–10 |
The 2008–09 season was Beşiktaş' 105th football season. Also it was the 50th year of the Süper Lig. Beşiktaş won the domestic double of the league title and cup.
** * * *
* Also holds German citizenship. ** Also holds Australian citizenship.
See main article: 2008–09 Turkish Cup. After finishing in the top four of the previous season's Süper Lig, Beşiktaş qualified for the group stages. Beşiktaş was placed in Group A, along with Antalyaspor, Gaziantepspor, Trabzonspor and Gaziantep B.B. Beşiktaş finished first.
Beşiktaş won 5-1 on aggregate
Beşiktaş won 4-3 on aggregate
After finishing third in the previous season's Süper Lig, Beşiktaş qualified for the 2008–09 UEFA Cup, but was eliminated in the first round.
Beşiktaş won 6-1 on aggregate
Beşiktaş lost 2–4 on aggregate