The 24-year-old winger, who joined the Greens from Nimes last month, opened his goal account in his second game for Ghislain Printant’s men to help his side avoid defeat at Stade Geoffroy Guichard.
After Julien Faussurier put the visitors in front with his 45th-minute effort, Bouanga, who was handed his second start, equalised for Saint-Etienne with seven minutes left to play.
The Gabonese forward featured for the duration of the game along with another summer signing and Algeria international Ryad Boudebouz while Ivorian Jean Eudes Aholou was replaced in the 40th minute.
Tunisia’s Wahbi Khazri made way for Arnaud Nordin in the 75th minute while Algerian striker Haris Belkebla was on parade from start to finish for Brest.
With the draw, the Greens are unbeaten in their opening two games of the season after claiming victory against Dijon last weekend.
Bouanga will look forward to another impressive performance when Saint-Etienne try Lille for size on Wednesday, August 28.