The 31-year-old joined the Ligue 1 side from Club Brugge in 2012, and made 18 league appearances last season as Monaco snatched the French title away from capital giants Paris Saint-Germain.
Just eight of those 18 league appearances were starts, however, and the experienced midfielder has now moved on to Turkish football.
"We have an agreement in place with Dirar and Monaco, and we are delighted to confirm that he will be joining us," read a statement on Fenerbahce's official website.
Meanwhile, Dirar told Fenerbahce TV: "I am proud to have the chance to play in a big club like Fenerbahce.
"I have had the chance to play here in Istanbul with Monaco - the facility, great atmosphere and the enthusiastic fans left a good impression on me. There are top talented players here and I am confident that together we will achieve great things."
It is understood that Dirar has agreed terms on a lucrative three-year contract.