Giroud, who has embraced the "new challenge" at Stamford Bridge, also thanked the Gunners for his "amazing" time under Arsene Wenger.
"It's been a while since I played regularly and that's why I needed to move," the 31-year-old told The Mirror.
"I needed a new challenge and Chelsea was the perfect club for me. It's the Premier League, a club which has won more titles in the past ten years than any other.
"It's a massive club and I am very proud to be here and to carry on my career in the Premier League. I had five amazing years [at Arsenal], but now it's a new chapter of my career and I am focused 100% on the Blues to reach our targets. I'm very happy to be here."