Leuluai, younger brother of Wigan scrum-half Thomas, first joined Leigh in 2009 and made 38 appearances for them before moving to the Vikings.
Centurions coach Paul Rowley said: "MacGraff adds a bit of value to us. I've a lot of time for him. He is a nice lad and a talented player. It will be a breath of fresh air for him and we are offering him an opportunity to get some confidence and continuity into his game."
He has appeared in just eight Super League games this season, seven off them off the bench.
Leigh have released prop Steve Nash back to Castleford to make way for the arrival of the back-row forward, who is set to go straight into the team to play York on Sunday.