The 23-year-old Olunga came on as a second-half substitute in his new club’s friendly game against Ripoll and fired in two goals in an 8-0 victory.
The Harambee Stars international is on a season-loan deal from Chinese Super League side Guizhou Zhicheng.
Olunga could make his official La Liga debut on Sunday as his side take on Atletico Bilbao away from home.
Girona have claimed four points from their opening two matches.
Former Gor Mahia forward Olunga has, meanwhile, explained why his number 14 jersey has two names ‘Olunga Ogada’, printed on his back.
“I added Ogada in remembrance of my late Dad who was a football lover. Wherever you are I will strive to make you happy,” Olunga stated on social media.