Both goals came in the opening 21 minutes with Campbell in the right place at the right time to apply close range finishes to take his tally for the season to eight.
Nigel Adkins made two changes following the draw at Millwall a week earlier. Ondrej Mazuch replaced the injured Jordy de Wijs, while Stephen Kingsley returned from injury to take the place of Brandon Fleming who dropped to the bench.
Brentford went close early on after the Tigers had given possession away deep in their own half, Mohamed Benrahma curling an effort just wide. Kamohelo Mokotjo then saw a shot deflect past David Marshall’s right-hand upright as the visitors knocked the ball around nicely in the opening minutes.
However, it was the Tigers who took a 12th-minute lead. A real up-and-under from Todd Kane caused chaos in the Brentford defence and a ball that was only partially cleared was knocked back in intelligently by Markus Henriksen for Kamil Grosicki, and although he miss-hit his volley there was enough on it for it to get past goalkeeper Daniel Bentley and into the path of Campbell who finished from close range.
Jackson Irvine headed a difficult chance over at the near post after being found by a Kane free kick but it would soon be 2-0 to the home side as Grosicki and Campbell combined again with 21 minutes gone. This time the Polish international got the better of Henrik Dalsgaard out wide before cutting inside and shooting low from the edge of the box. His effort was pushed away by Bentley, but Campbell was following up again to apply a simple finish.
Campbell went looking for a first half hat-trick when Daniel Batty’s cross found him 12 yards out but a volley went well wide before Marshall made a decent save to deny Nico Yennaris at the other end.
Grosicki miss-controlled a ball inside the Brentford box when it looked like things were opening up for him to add to the scoreline, but things looked positive for Adkins’ men as they headed into the break.
Marshall reacted well to keep out Benrahma’s deflected effort early in the second half before Brentford made a double change which included the introduction of former Tiger Moses Odubajo.
Benrahma skied a great chance high over the bar and then sent a free kick just over from the edge of the box before a first change from the home side saw Kevin Stewart replace Grosicki with 17 minutes left.
Will Keane then came on in place of Campbell before a final change saw Brandon Fleming come on for Batty.
Brentford enjoyed plenty of possession in the latter stages but could find no way through a resolute home defence as the Tigers extended their unbeaten run to four games.
Hull City: David Marshall, Todd Kane, Ondrej Mazuch, Tommy Elphick, Stephen Kingsley, Daniel Batty (Brandon Fleming 89), Markus Henriksen, Jarrod Bowen, Jackson Irvine, Kamil Grosicki (Kevin Stewart 73), Fraizer Campbell (Will Keane 80).
Subs Not Used: George Long, Nouha Dicko, Robbie McKenzie, Chris Martin.
Brentford: Daniel Bentley, Rico Henry, Chris Mepham, Nico Yennaris (Josh Dasilva 76), Neal Maupay, Ollie Watkins, Kamohelo Mokotjo (Sergi Canos 62), Romaine Sawyers, Mohamed Benrahma, Henrik Dalsgaard (Moses Odubajo 62), Julian Jeanvier.
Subs Not Used: Luke Daniels, Josh McEachran, Ngoyo Konsa, Yoann Barbet.
Referee: Mr A. Davies.