Kerem Akturkoglu gave a 1-0 lead to the Lions in the ninth minute but Isaac Thelin scored an equalizer for the away side in the 51st minute.
Galatasaray secured a hard-fought win after Mostafa Mohamed converted the penalty in the 89th minute. The Lions remain on top of the Super Lig with 51 points by winning six matches in a row, while Kasimpasa are in the 15th spot with 26 points.
Sunday's results in Super Lig:
Ittifak Holding Konyaspor - Yukatel Denizlispor: 2-0
Atakas Hatayspor - Aytemiz Alanyaspor: 0-0
Goztepe - Medipol Basaksehir: 2-1
Galatasaray - Kasimpasa 2-1
