The Congolese international returns to Rugby Park where he will spend the rest of the season.
Mulumbu has made just three appearances for Brendan Rodgers this campaign after signing a two-year deal in the summer. He left Rugby Park at the end of last season after starring for Steve Clarke.
The 32-year-old made 20 appearances for Killie, becoming a fans’ favourite.
The former PSG, West Brom and Norwich City midfielder will boost Killie’s hopes of challenging for the Scottish premiership title.
He becomes the club’s fourth January signing following the arrivals of Liam Millar, Conor McAleny and Alex Bruce.