"He (Mbappe) speaks on the football pitch," said France coach Deschamps. "He knows that himself but he can change a match in just a moment. He is always playing with such joy.
"France needed a great Kylian Mbappe tonight and they got one."
Giroud's record goal was more clinical than sensational but came when France needed to score.
"The adventure continues," said Giroud. "We had said in the dressing room that to live such a great experience we needed to be united, be as one.
Having dominated the opening half, Les Bleus appeared to be heading into the break without any reward until the 44th minute when Mbappe played the ball through into the path of Giroud, who hammered it home to claim his 52nd goal and move past Thierry Henry as France's top scorer of all time.
In the second half, it was the Mbappe show with superb 74th-minute and stoppage-time goals that sealed Poland's fate.
They were his fourth and fifth goals in Qatar, and Mbappe became the first player to score nine World Cup goals before his 24th birthday, having netted as many as Argentina's 35-year-old Lionel Messi.
Mbappe, who scored four times during France's run to World Cup victory in Russia four years ago, turns 24 two days after the Qatar final.
It was the second game at this tournament in which Mbappe had netted twice, having also counted a brace against Denmark, leaving him the hot favorite to win the Golden Boot as the World Cup's top scorer.
But Mbappe said it was the gold World Cup itself that had his full attention, not any other trophy.
"The only objective for me is to win the World Cup," said Mbappe. "The only thing I dream is this.
"I came here to win this World Cup; I didn't come here to win a Golden Ball or the Golden Boot.
"Of course if I win it I am going to be happy but that is not why I am here."