The UFC announced the pairing on Friday as a supporting act for the Renan Barao vs. Michael McDonald main event in London.
Diabate has won three of his last four, most recently defeating Chad Griggs by submission at UFC 154. Diabate (19-8-1) has finished 14 of his 19 career wins in MMA, and 31 of 41 during his pro kickboxing days.
The unbeaten Manuwa (12-0) debuted in brilliant fashion at September's UFC on FUEL 5 event, battering Kyle Kingsbury with a vast assortment of strikes for two rounds before the cageside doctor stopped the bout prior to the third.
The exciting prospect has never been to a decision, with 11 KO's and one submission on his career ledger.
The show, which will emanate from the Wembley Arena, has had six other fights confirmed by the promotion. They are: Che Mills vs. Matt Riddle, Terry Etim vs. Renee Forte, Paul Sass vs. Danny Castillo, Phil Harris vs. Ulysses Gomez, Vaughan Lee vs. Motonobu Tezuka and Andy Ogle vs. Josh Grispi.