Dack's goal at the KCOM was his fourth in all competitions so far this season
Bradley Dack scored the only goal as Blackburn Rovers earned their first Championship victory since promotion against Hull.
Dack's close-range finish - his fourth goal in all competitions so far this season - came just before the break and followed Elliott Bennett's cross from the right.
A frantic finale saw good chances come and go for Hull's Jordy de Wijs and Nouha Dicko.
The result means Tony Mowbray's side recorded their first second-tier victory since they were relegated on the final day of the 2016-17 season.
The visitors enjoyed the better of the first half, and could have taken an earlier lead had Kasey Palmer not been denied by David Marshall in the Tigers' goal.
But there were worrying scenes midway through the opening half, after a sickening clash of heads between Palmer and Hull defender Stephen Kingsley resulted in the latter being forced off injured.
After the break, Australia international Jackson Irvine forced Blackburn goalkeeper David Raya into action with a smart save.
However, it should have been 2-0 midway through the second half when Adam Armstrong showed a turn of speed to get into the area before his shot was saved by Marshall, and Bennett put the rebound wide.
The visitors negotiated six added minutes to secure victory, as Hull remain without a league victory since 10 April.
Hull boss Nigel Adkins told BBC Radio Humberside:
"I won't hide in any corner. My shirt's wringing wet - I've been sweating like mad trying to get something from the game with the team.
"The scenes at the end where the crowd had turned on the players and turned on us is not what we want. We want to try and be together, especially so early in the season.
"[It] highlighted that it's going to be a tough season. It was a tough game for the guys today. We gave a poor goal away at half-time and we needed to get to half-time because, for me, they [Blackburn] were in the ascendancy."
Blackburn boss Tony Mowbray told BBC Radio Lancashire:
"There were lots of components to the game that were good today.
"[There was] the fact we came away from home, started on the front foot and could have scored two or three in the first half.
"Then to get the goal, to keep going and add some great opportunities, second-half - we had some great opportunities that weren't to be, but we're standing here with three points."
