The Rams were happy to invite pressure from Leeds, and although they failed to register a single shot in the first half, Mateo Josef gave the visitors three chances in a goalless first period.
Leeds increased the pressure in the second half, but Derby remained solid, thanks in large part to Jacob Wider-Zetterstrom, who made four saves, including a one-on-one from Dan James.
However, Leeds' momentum was undeniable and it was Aaronson who was the hero, scoring his seventh goal of the season with 11 minutes remaining, completing a brilliant team move.
Manager Daniel Farke decided to start Raji Ramazani for the first time since October, alongside Josef, Tanaka'o and Wilfried Gnont, but Derby remained unchanged from Boxing Day's win over West Brom. .
The home faithful made their feelings known to former right-back Jayden Bogle, who beat the Rams defense with his runs, but his cross was unable to be turned home by Joseph.
Zetterstrom first took action when he dropped low to thwart Josef's low drilling from long range.
Derby chances were very rare throughout the first 30 minutes, with Kayden Jackson's cross sailing just wide of the goal, causing goalkeeper Illan Meslier to scramble momentarily.
Clever link-up play between Gnont and Josef created a chance for Aaronson, who sent a harmless slice over the bar.
Leeds started the second period just as they had ended the first, and Aaronson should have taken the lead, but Aaronson's strike was brilliantly saved by the diving Zetterstrom.
A minute later, Leeds thought they would have another chance when Joseph latched onto a through ball but was hit again.
Derby started to show more ambition as the clock ticked past the hour mark, with Meslier forced to parry Curtis Nelson's header from a dangerous corner kick.
Chances continued to come for the visitors, but Derby were grateful that Zetterström twice rejected Ramazani and replaced him with James.
Derby finally succumbed to Leeds' pressure in the 79th minute.
United looked for a breakthrough by toying with County with a combination of passes, but Joel Pillow took a deft touch from a pass from fellow substitute Manor Solomon, and Aaronson calmed down before slotting the ball deftly into the bottom corner. I scored a goal.
