Nicholson's coolness from the penalty spot ensured Chesterfield got three points at Saltergate for the first time since November and left Huddersfield to reflect on a seventh straight away defeat.
It was a miserable afternoon for the Yorkshire club who also had two players sent off in the second half and although they staged a late rally it was not enough.
Chesterfield were certainly far from convincing and would have been trailing at half time if Huddersfield had made the most of some good positions.
Former Chesterfield winger Chris Brandon should have done better in the second minute and Andy Booth also failed to hit the target seven minutes before the interval.
Those misses proved costly when 17-year-old full-back Tom Clarke was given a straight red card after Jamie McMaster went tumbling in the 53rd minute.
It looked a harsh decision on both counts but Nicholson beat Paul Rachubka to his right and the game had changed.
Nicholson made no mistake a second time when McMaster was this time clearly tripped by David Mirfin who made amends with a clever back header from a free-kick two minutes later.
But Huddersfield's task became even harder when substitute Efe Sodje caught Nicholson on the right-hand touchline and was sent off for a second yellow card.
The visitors kept battling away but it was not their day and Chesterfield hung on to reach the magic 50-point mark.