The forward played for 90 minutes to help the Yellow-Reds claim the Turkish Cup title at the Yeni Sivas 4 Eylul Stadium on Wednesday.
Galatasaray are leading the Turkish Super Lig table with goals difference as they are tied with Istanbul Basaksehir on 66 points.
The on-loan Everton winger has charged his side to be ready against Abdullah Avcı’s men, as they aim to boost their chances of claiming their second title of the season.
“Cup Final Champions, all Praises to God! The Marathon Continues- The big one on Sunday,” Onyekuru posted on Instagram.
The Nigeria international has scored 15 goals across all competitions this season.
The three-time African champions are in Group B along with Burundi, Guinea and Madagascar.