The club's vice-captain will leave for military duties, ending his eight-year stay with the 2010 KPL champions.
Mohammed joined Ulinzi Stars in 2011 from Coastal-based side Congo United and remained part of the Soldiers side all through.
He played his last match against Burundi at Kasarani in the East African Community Military Games on Friday, which Kenya won by a solitary goal.
“As curtains fall in the 2019 military games, we’d like to announce the game against Rwanda was the last this season for our assistant captain Hassan Mohamed," Ulinzi Stars announced on their Facebook page.
"He will be away for a year on military duty and will thus not be listed for the 2019/20 KPL season. However, he remains a part of the club and will be incorporated into the team when he completes his assignment."
The player also confirmed the development on his Facebook page on Friday.
"It's definitely with mixed emotions, courage and strength I am writing this message. It has been an incredible journey here, with lessons learnt and memories to cheer and it is a little emotional I must bid farewell now," the central defender said on the Facebook post.
"But, I say goodbye as a person who has given his all efforts in every training session and in every game for the badge and for the club.
"And with gratitude, I would like to further extend my sincere, heartfelt appreciation to everyone at Ulinzi Stars FC, from management, administrators, technical bench and all my teammates who helped me so much to be who I am today, and the amazing fans who made me feel so special week in week out."