Diakite has been on the books of QPR since the start of the 2012-13 campaign, after completing a six-month loan deal with the London club, but has only played 14 league games and spent the second half of last season on loan at Watford.
Having failed to make a league appearance for QPR last season, the 25-year-old has been sent to the Saudi Professional League.
QPR confirmed the loan on their website.
Al Ittihad are one of the biggest clubs in Saudi Arabia but have not won the league since 2008-09.
Diakite's initial stint with QPR, on loan from Ligue 1 club Nancy, saw him play nine Premier League matches and score one goal.
But since then, Diakite has played just 20 total league games for QPR and Watford.
"Having struggled to impress again since [joining QPR permanently from Nancy], Diakite will now spend the campaign away from Loftus Road after time on loan at Watford last season," QPR wrote on their website.
