The Baggies lost 4-0 to Norwich City at the weekend to extend the club's losing streak to three games, and they have won just one of their last eight Premier League matches.
Ferguson manages his United side for the last time at The Hawthorns on Sunday, but Brunt insists that he will get no easy ride as he searches for a farewell victory.
"Sir Alex Ferguson is a one-off guy and we will pay our respects," Brunt said. "But we want to win this match like any other.
"After the performance against Norwich, I am sure the least we will get is 100% effort.
"At Norwich maybe we stepped off the gas."
Brunt has recently returned to the West Brom side after a knee injury during April, and has made 30 league appearances this season.