Martyn Waghorn scored a goal in each half to secure the points for the Rams as the Tigers fell seven points behind their opponents in the play-off race.
Nigel Adkins named the same eleven that started last weekend’s victory over Stoke City, with the only change in the squad coming on the bench where Nouha Dicko replaced Chris Martin who was unable to face his parent club as part of the terms of his loan agreement.
There were a few familiar faces in the Derby line-up with former Tigers Tom Huddlestone, Harry Wilson, Fikayo Tomori and Waghorn all starting.
Huddlestone had the game’s first shot in anger with five minutes played when he took aim from 20 yards, sending a left-footed effort over David Marshall’s bar.
The Tigers responded by creating a great chance eight minutes in. Markus Henriksen nipped in to break up Derby’s play in the middle of their own half and set Fraizer Campbell away down the middle. He was unselfish in knocking the ball left for Kamil Grosicki but he failed to hit the target with a low shot from eight yards.
Huddlestone curled another attempt off target and Marshall made a simple save from a Tomori header before making a slightly more complicated stop from Duane Holmes’ deflected shot.
Campbell fired an effort across the face of goal at the other end but it was Derby who opened the scoring four minutes before half time. Holmes’ through ball saw Waghorn beat the offside trap and although Marshall did well to save a first attempt, the striker made no mistake when the ball dropped invitingly back to him.
Marshall saved from Holmes and Tomori headed a great chance wide when meeting a Wilson corner unmarked early in the second half as Derby looked to extend their lead.
Jackson Irvine was inches away from bringing the Tigers level just after the hour when he glanced a Grosicki cross just wide at the end of an attack that had started with Kevin Stewart winning the ball well in midfield.
Waghorn saw a low shot turned wide well by Marshall but the striker was soon on the scoresheet again when he doubled the Rams’ lead 19 minutes from time. The Tigers lost the ball by their own corner flag and when it was pulled back to Waghorn he fired a first time finish past Marshall.
That was followed immediately by a double change from Adkins as Marc Pugh and Evandro came on for Jarrod Bowen and Stewart, and a first appearance for Liam Ridgewell also came when replacing Stephen Kingsley.
Irvine volleyed a great chance over the bar from Evandro’s nod-down with what was the Tigers’ best chance of the second half, and they’ll now look to bounce back when they host Rotherham United on Tuesday night.
Derby County: Kelle Roos, Craig Bryson, Fikayo Tomori, Richard Keogh, Harry Wilson, Martyn Waghorn (Ashley Cole 90), Florian Jozefzoon (Mason Bennett 59), Duane Holmes (Andy King 81), Jayden Bogle, Tom Huddlestone, Scott Malone.
Subs Not Used: Henrich Ravas, Andre Wisdom, Bradley Johnson, David Nugent.
Hull City: David Marshall, Todd Kane, Eric Lichaj, Robbie McKenzie, Stephen Kingsley (Liam Ridgewell 75), Kevin Stewart (Evandro 72), Markus Henriksen, Jarrod Bowen (Marc Pugh 72), Jackson Irvine, Kamil Grosicki, Fraizer Campbell.
Subs Not Used: George Long, Nouha Dicko, David Milinkovic, Daniel Batty.
Referee: Mr G. Ward.