The Ligue 1 side unveiled Traore on Monday, signing the 21-year-old striker in a €10 million move.
Traore's arrival comes after a successful loan stint at Ajax last season, and also means the French side will no longer try to land Giroud after being linked to the Arsenal striker.
"We don't want to stockpile forwards," Lyon owner Jean-Michel Aulas said at Traore's unveiling when quizzed about Giroud.
"Arsenal want to keep him," Aulas added.
Giroud has been tipped to leave Arsenal this summer after starting just 11 of his 29 Premier League appearances in 2016-17.
West Ham are among the clubs to be credited with an interest in the 30-year-old, with Goal reporting the Hammers made a £20 million bid earlier this month.