Hulse headed his 18th of the season in the second half to settle a disappointing match that was short on quality and incidence.
Derby had looked like a side stumbling towards the finishing line in the first 45 minutes when Charlton's neat possession football had dominated without really threatening to deliver goals.
The closest the visitors came was when China international Zhi Zheng turned away from Lewin Nyatanga but his shot was charged down by Stephen Bywater.
Derby had not troubled Rob Elliot but, no doubt with a few choice words from manager Nigel Clough ringing in their ears, they upped the tempo in the second half.
Hulse almost scored with a close-range header in the 49th minute and then defender Martin Albrechtsen also went close from another Gary Teale corner.
Charlton were finding it difficult to clear their lines and were fortunate to survive a strong appeal for a penalty when Teale appeared to be pulled back by Danny Butterfield.
Referee Fred Graham ignored their claims but three minutes later, another 31,000 plus crowd had the goal they had been waiting for.
A Teale corner was only half cleared and when Barry Bannan headed it back in, Hulse flicked a header inside Elliot's left hand post.
Charlton responded impressively but apart from some long range efforts, they did not look like scoring and it was Kris Commons who almost got a second for Derby six minutes from time with a shot from just outside the area that flashed narrowly wide.