Fraytt has penned a three-and-a-half year deal at the KC Stadium for an initial £1.2million, a fee which will eventually rise to £1.6m.
The striker reunites with former Foxes boss Nigel Pearson but is ineligible for the New Year`s Day meeting between the two sides under the terms of the transfer.
The 24-year-old`s arrival follows hot on the heels of Aaron Mclean`s move from Peterborough to further boost the Tigers` firepower up front.
But one player leaving the Humberside club is winger Kilbane who could make his Terriers debut in the New Year`s Day clash at Carlisle should the relevant paperwork be completed in time.
Kilbane has made 15 appearances for Hull this season, scoring once.