Mbappe is the leading scorer at this year's finals with five goals, including a brace in Les Bleus' last-16 victory over Poland, while he has also assisted two of Giroud's three strikes in Qatar.
That included a precise throughball for the Milan forward to net his record-breaking 52nd international goal against the Poles, moving him ahead of Thierry Henry on France's all-time scoring list.
"My relationship with Mbappe is very good and, for me, it always has been," the 36-year-old said.
"It's natural and spontaneous. High-level sport brings magical moments to life and it is this enthusiasm that we want to convey in this team."
Reigning champion France is now just three victories away from becoming the third nation to successfully defend its FIFA World Cup crown, and first since Brazil in 1962.
Giroud says Didier Deschamps' side believes it can achieve the feat, but he is wary of the challenge to be posed by the Three Lions, who have scored 12 goals in their four matches so far.
"We are confident, but there are still three games to win," he added. "We know it would be huge for history to do it, but we're just focused on the game against England.
"The profiles of the players on the wide areas are those who are fast, tackle and take up spaces. They are also dangerous on set-pieces, with size.
"There are amazing players in all areas of the game. We will have to be vigilant in defence, but so will they."