The game was originally meant to be played on Boxing Day and was postponed again on Wednesday night when referee Willie Collum ruled the Tannadice pitch was waterlogged.
The decision means United will play four Clydesdale Bank Premier League games in 13 days, with another match against Rangers still to be rearranged.
St Johnstone's home tie against Aberdeen has been scheduled for Wednesday, March 2 after a waterlogged pitch forced it off on Saturday.
Source: PA
Source: PA