He took his tally to an impressive 39 goals in 139 Premier League appearances, 38 of those coming as Leicester lifted the trophy in stunning fashion back in 2016.
The Algerian winger is understood to have signed a £200,000-a-week, five-year deal at the Etihad with an option to extend.
Manchester City have been in negotiations for the Algeria worldwide all summer but are close to thrashing out the final details, with a deal likely to be signed off before the weekend.
Initially it looked as though the failed deal would wreak havoc when Mahrez went AWOL and failed to turn up for Leicester training for 10 days, but he soon returned and pledged his commitment to the club.
"I am so pleased to have joined City, a side playing great football under Pep Guardiola. Pep is committed to playing attacking football, which is a flawless for me, and City's performances last season were outstanding", he said on the club's official website.
City's director of football Txiki Begiristain added: "Riyad is a hugely talented player". They're redefining the English game and I wanted to be a part of it.
Mahrez's experience of winning the Premier League will certainly have left him hungry for more success, and he now has the chance to achieve that once more under the stewardship of Pep Guardiola.
Good signing for Leicester City?