The 27-year-old defender completed his move on Wednesday which involves an option to make the deal permanent.
Sidibe won the Ligue 1 title 2017 and was part of the France squad who won the World Cup in Russia last year.
He was also an important part of Monaco’s run to the Champions League semi-finals in the 2016/17 season.
"I am 100 per cent motivated and ready to help the club achieve its goals and to achieve my own individual goals," Sidibe said.
"Everton are recruiting with the intent to win trophies and play on the biggest stage."
The French international becomes the sixth new arrival to Merseyside this summer, joining the likes of Fabian Delph, Andre Gomes and Moise Kean.
"Djibril has fantastic experience, winning titles and playing many matches in a competitive league," Everton boss Marco Silva told the club website.
"He is a World Cup winner and he has the hunger to achieve much more in his career."