The Switzerland international moves to the King Power Stadium for an undisclosed fee subject to clearance from the Premier League.
Goal revealed on Saturday that Claudio Ranieri's side had agreed a long-term deal with Inler, with the club looking to replace the departed Esteban Cambiasso.
Inler brings plenty of experience with him to Leicester, having earned 84 caps for his country as well as representing Napoli in the Champions League.
Inler becomes Leicester's sixth signing of the transfer window, and joins a team that have started the season with back-to-back victories.
Claudio Ranieri's side started with a 4-2 win over Sunderland, before triumphing 2-1 at West Ham on Saturday.
Inler could make his debut against Tottenham on Saturday.