Besiktas, the least decorated yet oldest of the "big three" teams in Istanbul, qualified for the Champions League while Basaksehir, who finished second, go into the qualifying rounds.
Besiktas players and fans celebrated the team winning its 15th Turkish league title on Saturday.
As part of the celebrations, a flotilla of about 100 ships moved along the Bosphorus in Istanbul.
The flotilla departed from the Asian side of the city and headed to Istanbul's Besiktas district on the European side to celebrate the team's second consecutive Turkish League title.
Around 50,000 fans showed their joy by lighting firework, flares and thousands of torches while holding flags and chanting slogans.
Besiktas clinched the championship last week by beating Gaziantepspor 4-0.
The Black Eagles will now add a third star to their logo, having reached 15 league titles. A star is awarded for every five titles.
Besiktas closed the season at home against Osmanlispor with a 4-0 dominating performance.