Mangane, 29, joins the club for an initial cost of €300,000.
The Black Cats also hold an option to make the deal permanent in the summer for €3 million, the same figure Al-Hilal paid for him from Rennes in July last year.
Earlier, O'Neill revealed the signings of midfielder Alfred N'Diaye and Mangane are part of a concerted effort to add height and power to his Sunderland squad.
N'Diaye, 22, stands at 6' 2'', while Senegalese defender Mangane is 6' 5'', and O'Neill admitted earlier in the season that, without club captain Lee Cattermole in the side, Sunderland lacked a certain physicality.
Martin O'Neill: "Kader is player who will add to the overall strength of our squad and give us options.
"He will improve competition for places and we are delighted to welcome him to the club.
"Alfred coming in, it's not just absolutely and utterly to do with the size aspect of things.
"I think he has the talent and the energy as well and I think he could be a really decent hit here.
"The reality is we are a bit small as a squad, maybe the smallest in the Premier League, and we had problems with the physical aspect in some games earlier in the season.
"We found it difficult. But, having said that, mighty atom David Vaughan came in against West Ham - all of about 5' 7'' of him - and was as good as anyone on the pitch.
"We are looking to add strength in depth and Alfred coming in has certainly given us a lift."
Source: Sunderland-Mad
Source: FOOTYMAD
