Dan Sarginson and Ollie Gildart scored Wigan's key tries after the break
Wigan Warriors will go into next Friday's Super League play-off semi-final on the back of an eighth straight victory after narrowly seeing off Hull.
Two converted tries in nine minutes from Carlos Tuimavave and Jamie Shaul earned Hull an interval lead, Wigan having crossed through Gabe Hamlin.
But the Cherry and Whites bounced back after the break to sentence injury-hit Hull to an 11th straight defeat.
Centres Dan Sarginson and Ollie Gildart both went over to complete the scoring.
But young scrum-half Josh Woods' first-half conversion was their only successful kick - and it meant for a tight finish as Hull looked the better team in the final 10 minutes but could not find a way through.
Wigan, who were already guaranteed second place in the table, will now welcome Cas to the DW Stadium in a week's time without a league defeat since losing at home leaders St Helens on 19 July.
