The 32-year-old former Swansea City and Lyon player fainted early in the first half of the 2-1 defeat against Istanbul team Kasımpaşa but returned to the field shortly afterward after doctors gave permission.
The French player was seen bending over before falling to the ground in the seventh minute.
The medical team quickly intervened, and his teammates gathered around him but Gomis, who was taken off, was able to return within minutes and play the rest of the match.
Gomis suffers from a vasovagal condition that makes him prone to fainting. Previous episodes took place during his career at Lyon and also when he was playing for Swansea against Tottenham in 2015.
Gomis has had the condition, linked to low blood pressure, since childhood.
He signed for Galatasaray in June last year from Swansea on a three-year deal.
The Turkish team’s doctor said the club was fully aware of the situation when he signed.
“This sometimes happens to me, it’s a situation completely linked to stress,” Gomis said after the game.
“I did not have any issues after the incident, and I got out and played,” he was quoted as saying by Doğan news agency.
Gomis said he was more concerned by the result than his health.
“My only sadness today is that we were not victorious,” Gomis said, vowing that “I will continue like a lion.”