However the 50-year-old has overseen a poor run in the Premier League since August. After 12 games, Fulham are bottom of the table with five points.
Ranieri, who steered Leicester City to the Premier League title in 2016, was available after being sacked by the French Ligue 1 club Nantes one game before the end of last season.
Ranieri's managerial career spans more than three decades. The 67-year-old has worked in Italy, Spain and Greece. But winning the title with Leicester City two years ago remains his biggest achievement.
The side started the 2015-2016 Premier League campaign with odds of 5000-1 to win the title. But they confounded the bookmakers with performances of guile, guts and panache. They have slid to mid table respectability in the aftermath of key departures from the championship winning squad.
Ranieri will take charge of his first game in 10 days when Fulham welcome fellow strugglers Southampton to Craven Cottage.