Giroud got on the end of a cross from his soon to be former Arsenal teammate Bacary Sagna and struck a sweet volley past Hugo Lloris, who had no chance in saving the powerful strike.
The French striker had a turbulent season with the Gunners and was in the spotlight for all the wrong reason's midway through the season.
But with his marriage now seemingly in good shape, the former Montpellier man can concentrate on scoring goals for France at the World Cup.
He scored twice in last week's 4-0 win against Norway and will hope to take the form he showed in that game into the tournament which kicks off in seven days.
His goal in training showed all the signs of a striker with full confidence as his powerful volley flew into the back of the net.
Les Bleus open their World Cup campaign against Honduras on June 15 and Giroud will be competing with Loic Remy and Karim Benzema for the starting role in attack for France.
They face Jamaica in their final friendly before the tournament on Sunday night, and Giroud will want to show Didier Deschamps why he deserves to lead the line for Les Tricolores.