The Tigers found themselves 2-0 down inside 20 minutes before a freak goal from Ryan Tafazolli brought the home side back into the game before half time. However, the Bees ran away with things after the break.
Grant McCann was forced to shuffle his pack following the deadline day departures of Jarrod Bowen and Kamil Grosicki. In total, there were four changes to the side that started against Huddersfield Town in midweek. Keane Lewis-Potter made his first league start, with Stephen Kingsley, George Honeyman and Jackson Irvine also coming in. Robbie McKenzie and Herbie Kane dropped out.
New loan signing Marcus Maddison was included amongst the substitutes, as was Norbert Balogh who last featured in October.
Josh Magennis headed a Kingsley cross over in the opening five minutes, although an offside flag meant it wouldn’t have counted even if it had been on target.
Bryan Mbeumo knocked a chance wide for the visitors as he got on the end of a deep cross from the left, before Tafazolli produced a well-timed challenge to deny Ollie Watkins inside the box. From the resulting corner, Brentford took a 12th-minute lead. It was worked shot, and Said Benrahma cut inside before firing past George Long from the edge of the box.
It was nearly two a couple of minutes later but Kingsley did well to deny Mathias Jensen, before Long made up for his own error in playing out from the back by saving from Mbeumo.
Brentford did double their lead in the 20th minute. Again a short corner caused problems, and this time it was crossed to the far post where it was headed back and Reece Burke flicked it into his own net.
Eric Lichaj sent a shot high and wide from Irvine’s ball to the edge of the area before Burke almost made it a goal at each end as he swivelled to meet a Tafazolli nod down but sent a shot wide.
The Tigers got back into the game in bizarre circumstances just before the half-hour. Tafazolli’s ball forward from halfway was going nowhere, but Brentford goalkeeper David Raya took his eyes off it and allowed it to roll underneath his foot and into the net.
Tafazolli was on duty at the other end moments later as he made a goal-line clearance from Benrahma’s shot, ensuring that the home side only trailed by a goal at half time.
Irvine fired over seconds after the restart, while Raya snuffed out a dangerous low cross from Lewis-Potter.
It was a brighter start from the Tigers, but Brentford went 3-1 up in the 58th minute. Rico Henry crossed from the left and Watkins was there to head in from six yards.
That brought a double change as Maddison and Tom Eaves replaced Mallik Wilks and Magennis.
Five minutes later it was 4-1. The Tigers were ripped open and Benrahma was in place to apply a neat finish.
Joel Valencia saw an effort blocked on the line as the visitors threatened to add a fifth goal, while at the other end Maddison saw an effort tipped over the bar by Raya.
The game was long since up, though, and Brentford added a fifth in the final ten minutes as Benrahma completed his hat-trick.
Hull City: George Long; Eric Lichaj ©, Reece Burke, Ryan Tafazolli, Stephen Kingsley; Leonardo Da Silva Lopes, Jackson Irvine (Herbie Kane 67), George Honeyman; Mallik Wilks (Marcus Maddison 59), Keane Lewis-Potter, Josh Magennis (Tom Eaves 59).
Subs Not Used: Matt Ingram, Daniel Batty, Sean McLoughlin, Norbert Balogh.
Brentford: David Raya: Henrik Dalsgaard, Ethan Pinnock, Julian Jeanvier, Rico Henry; Christian Norgaard, Mathias Jensen, Josh Dasilva (Emiliano Marcondes 72); Bryan Mbeumo (Joel Valencia 72), Said Benrahma, Ollie Watkins (Halil Dervisoglu 82).
Subs Not Used: Luke Daniels, Dru Yearwood, Luca Racic, Mads Roerslev Rasmussen.
Referee: Mr D. Bond.