Despite dominating the possession in Saturday's League Two clash at the Pirelli Stadium, Grimsby's fate was effectively sealed in the first half of a game they knew they had to win to have any chance of survival.
Greg Pearson opened the scoring in the 10th minute, latching onto a long clearance before smashing home a 20-yard shot into the top corner.
After surviving more waves of Grimsby pressure, Burton doubled their lead in the 37th minute when top-scorer Harrad bundled home his 21st goal of the season from Pearson's deflected cross.
Albion keeper Kevin Poole continued to thwart the visitors with saves from Michael Coulson and Jamie Devitt in the opening minutes of the second half.
And Poole's good work was backed up by the strikers as Harrad made it 3-0 with a superbly-struck 25-yard free kick in the 58th minute.