The Frenchman moved to Stamford Bridge in a deal worth £18m.
And speaking to Telefoot, the 31-year-old admitted his desire to remain in the Premier League made him choose Chelsea.
Giroud added that Antonio Conte was also integral to him making the move.
"My choice was quite clear and obvious when I knew that Antonio Conte wanted to work with me. I know that Conte appreciates my profile, we work well together.
"I spoke to [France manager] Didier Deschamps about my situation. He did not tell me to join Chelsea, just to change club."
He added: "The fact is that the coach wanted to recruit a new forward striker [Aubameyang] With his signing at Arsenal, it was three top strikers, and that's why I decided to leave.
"I could have stayed, but I needed some solutions to get back in. I wanted to stay in the Premier League and Chelsea was a great opportunity for me."