Jokanovic led Fulham back into England’s top flight in May 2018 but the 50-year-old Serbian has struggled to adapt to life in the Premier League.
After 12 games, Fulham sit bottom of the pile with just five points and one win from 12 games.
Ranieri, who famously led Leicester to a fairytale Premier League title in 2016, was a free agent after being sacked by French Ligue 1 club Nantes one game before the end of last season.
“It is an honour to accept Mr Khan’s invitation and opportunity to lead Fulham, a fantastic club with tradition and history,” Ranieri told the club’s official website. Play Now on NaijaBet
“The objective at Fulham should never be to merely survive in the Premier League. We must at all times be a difficult opponent and should expect to succeed.”
Khan thanked Jokanovic, the first managerial casualty of the season in the Premier League, for his work at the club.
“I wasn’t anticipating having to make this announcement related to Slavisa and wish the circumstances were such that I didn’t have to, but our path this season has led me to make what I know is the correct decision, at the right time, for our players, the club and our supporters,” said the Fulham chairman.
“Slavisa will always have my appreciation and respect for everything he did to return Fulham to top-flight football.”
Ranieri’s appointment comes only weeks after his former boss at Leicester, club owner Vichai Srivaddhanaprabha, died with four others when his helicopter plummeted into a car park outside the King Power stadium shortly after a match against West Ham.
“I was terribly shaken by the news,” Ranieri told Sky Sport Italia two weeks ago.
“He was a good man and always had a positive word for everyone.”
But winning the title with Leicester two years ago remains the affable 67-year-old’s biggest career achievement.
But he believes the Londoners can be competitive again. He will take charge of his first game in 10 days’ time when Fulham welcome fellow strugglers Southampton to Craven Cottage.
“This Fulham squad has exceptional talent that is contrary to its position in the table. I know this team is very capable of better performances, which we will work on straight away as we prepare for Southampton at the Cottage,” added Ranieri.
Ranieri will then face former clubs Chelsea and Leicester in successive games.