In November, Bignot left Solihull Moors to move to Blundell Park but despite possessing a record of nine wins and 11 defeats from 27 games, the League Two outfit have decided to make a change in the dugout.
A club statement read: "Following Grimsby Town Football Club's return to the EFL, there remains a strong ambition to build on last season's promotion.
"Therefore, it is with regret that today the club has decided to release the current management team from their first-team duties.
"The board would like to put on record their thanks to Marcus Bignot, Michael Moore and Gary Whild for all their hard work and efforts during the last six months and wish them the best for their futures."
Grimsby currently sit in 14th place in the league standings, seven points off the playoffs and 16 points above the relegation zone.