The game ended in a goalless draw after extra time, but the shoot-out was one-sided as The Terriers won 4-1 with The Stags missing their opening two spot-kicks.
After Wayne Corden and Liam Lawrence both missed from 12 yards it was Lee Fowler who stepped up and scored from the spot to send Huddersfield back into Division Two.
A busy opening to the match saw Andy Booth go close after just seven minutes when Stags keeper Kevin Pilkington came flying out of his goal but missed the cross, but Booth's header looped just wide.
Danny Schofield caused havoc with a mazy run into the Mansfield box, but it was soon Huddersfield's turn to panic as they needed three chances to clear a messy scramble.
Schofield looked the main danger for The Terriers, and he should have done better with a close range free header, but nodded straight at Pilkington.
The game was wide open as both teams tried to attack, but Mansfield almost got caught out as Pawel Abbott broke but his ball was just too strong for the well-placed Schofield who was forced too wide and the chance was lost.
Wayne Corden fired in a low cross from the left on 54 minutes and Liam Lawrence was just inches away from poking the ball into the net.
The Terriers went straight down the other end and Schofield danced into the box and threatened to finish a magnificent goal before Adam Eton flew in with his last-ditch intervention to clear for a corner.
Booth climbed for a trademark towering header on 68 minutes but again it went straight at Pilkington, who stooped low down to gather.
A minute later Schofield found himself unmarked inside the box after a miss-hit volley, but as he turned a shot goalwards, Tom Curtis dived in with a superb block to save the day.
Corden produced a peach of a cross on 76 minutes but Colin Larkin failed to connect with Terriers keeper Paul Rachubka flapping.
Booth broke the offside trap eight minutes from time but failed to hit the target, while Larkin did no better for Mansfield when he ran free a minute later.
Larkin slammed the ball into the net in injury time only to have the goal controversially chalked off after the linesman ruled that the ball had gone out when Laurent D'Jaffo's knocked down at the far post.
Pilkington produced a superb save from Anthony Lloyd's volley in the best chance of extra time, which was soured by Efe Sodje's worrying departure on a stretcher with what looked a neck injury after a collision.
Rob Edwards, Danny Schofield and Tony Carrs both rammed in clinical penalties for Huddersfield, while Wayne Corden saw his effort saved by Paul Rachubka and Liam Lawrence, their regular penalty taker, tried a cheeky chip which hit the bar.
Fowler then stepped up and made no mistake from the spot to seal a memorable win for Huddersfield as the curtain came down on the English football season.
Match Summary:
Huddersfield v Mansfield
