The First Division side took the lead just before halftime when Paul Ifill fired home from 25-yards after a cheeky back-heel from Dennis Wise. Millwall added to their total early in the second half when Tim Cahill rose to head home a Wise freekick.
Victory was sealed in the dying stages with a header from defender Darren Ward.
Team: Warner (Gueret, 46mins), Roberts, Ryan, Cahill, Ward, Nethercott, Ifill, Livermore (Elliott, 20mins (Craig, 88mins)), Harris, Quigley. Subs not used: Clancy, Cogan, Donovan.