The 24-year-old has been granted international clearance to complete his move to The Jakemans Stadium after spending several months in Ireland.
Igiehon had top-scored for Scarborough Athletic in Evo-Stik Division One North last season before securing a move into the Irish professional game with Sligo.
He has returned to England as a free agent and is eligible to make his United debut against Leamington on Saturday.
PIC: Scarborough Athletic.