Playing in France's opening match at New York New Jersey Stadium, Mbappe slipped the ball past the goalkeeper in the 66th minute and notched his 58th international strike with a screamer in second-half stoppage time.
"Congrats, Kylian. You made it. I'm really happy for him," said Giroud, working as a pundit for the BBC. He said Mbappe had promised him his shirt from the match.
Real Madrid striker Mbappe, 27, had been under extraordinary scrutiny heading into the World Cup but came alive in the second half as France beat Senegal 3-1 in Group I.
France next play Iraq on Monday in Philadelphia before facing Norway in their final group match on June 26.
FIFA World Cup 2026
The 2026 World Cup took place from June 11th to July 19th in the United States, Canada and Mexico. The tournament featured 48 national teams and was won by Spain, who beat Argentina in the final.
Full schedule and results | Group standings and bracket | Past winners of the tournament | Our team of the tournament | About the 2030 World Cup