Giroud says he needed a change of scenery.
Speaking after making his home debut for the Blues in their 3-0 win over West Brom, he said: “As a football player you need to move on and be ready from the first day at your new club. It's a new challenge and it's been special for me to leave Arsenal.
“I had five amazing years there but now it's a new chapter of my career and I am focussed 100 per cent on the Blues to reach our targets and I'm very happy to be here.
“I received a nice welcome and I'm very happy with that. I know that people support us and I will try to pay them back on the pitch.
“People want you to give the maximum in the shirt. I want to be efficient with assists and scoring.
“Obviously we don't have too much time for the integration but I feel very good and the boys are very good to me.
“It's been a while since I played regularly and that's why I needed to move. 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."