Ghezzal will be reunited with the Foxes' French manager Claude Puel, who was in charge of Olympique Lyonnais as the player moved through the Ligue 1 club's academy.
He will become Leicester's fifth close-season signing after Jonny Evans, James Maddison, Ricardo Pereira and Danny Ward, subject to Premier League approval.
British media reported that Ghezzal, who joined Monaco in 2017 and scored twice in 33 games for the principality club, would cost the 2016 Premier League champions 10 million pounds ($13.01 million).
The winger made his Algeria debut in March 2015 and has played 13 times for his country, scoring once, having featured in their group games at the 2017 African Cup of Nations.
"He’s an exciting addition to our group who will bring creativity and competition ahead of an important season for us," Puel told LCFC TV.
"I know his qualities from my time at Lyon, where he was in the academy, and I look forward to seeing him test himself in the Premier League."
Ghezzal, who scored 14 goals in 110 games for Lyon, said of the Midlands outfit: "It’s a good club and an ambitious one too. Leicester City has many great players and I hope we will have a great season."
He will link up with his new team mates ahead of their Premier League opener against Manchester United on Friday.
(Writing by Ken Ferris; Editing by Clare Fallon)
