The Lyon man was not afforded the warmest of receptions at the Saint-Etienne venue, due to the clubs' domestic rivalry, although the in-form striker silenced some of the boo boys with a well-taken first-half opener.
After Antoine Griezmann's effort was saved, Lacazette diverted the loose ball home, before Olivier Giroud wrapped up a routine victory for Didier Deschamps' men.
When asked about scoring his first international goal in Saint-Etienne, Lyon youth product Lacazette told Canal Plus: "It's true that it is a little weird but I'll take it anyway.
"Inevitably, I expected the public reaction, I am Lyonnais. But for me, this is no problem, it's nothing.
"Anyway, when you're prepared for it, it's easier to take."
On his goal, the 23-year-old added: "So much joy, pride and a sense of liberation!
"It's good to open, finally, my international account and I hope I can repeat that performance."
The Euro 2016 hosts will play Belgium and Albania next in friendlies during June.
