Lukas Podolski scored either side of half-time after Aaron Ramsey's classy opener to ensure Arsenal would remain ahead of Everton regardless of the Toffees' result against Manchester United.
Hull contributed well in the first half but Podolski's second goal soon after the break knocked the stuffing out of them, and they will need to improve before the sides meet again next month.
Germany playmaker Mesut Ozil returned to the Arsenal line-up for the first time since March 11 after passing a fitness test on his hamstring, while Hull strikers Shane Long and Nikica Jelavic were recalled having been cup-tied against Sheffield United.
The match was preceded by a minute's silence in memory of former City full-back Andy 'Jock' Davidson, whose 579 appearances represent a club record.
Visiting keeper Wojciech Szczesny then foiled Hull captain Curtis Davies from an early corner.
Play was bizarrely interrupted in the early stages when a section of pitchside advertising hoardings blew over, littering the pitch but fortunately without injury to any of the players.
Szczesny gathered Ahmed Elmohamady's deflected cross and was also out quickly to beat Long to a dangerous through-ball.
Ozil was denied a penalty when he tumbled over Elmohamady's challenge, with replays indicating some contact.
Jelavic's sharp shot on the turn then drew an impressive low save from Szczesny but Long took too long to line up his shot from Jake Livermore's sumptuous through-ball, firing high and wide.
In between, Steve Harper beat away a decent strike from Podolski's weaker right foot.
Elmohamady broke up a promising Gunners attack by poking the ball away from Podolski - but the visitors took the lead in the 31st minute.
A slick passing move ended with Ozil and Cazorla playing in Ramsey, who had been involved early in the move back at halfway, to fire low inside Harper's far post.
An Arsenal win, perversely, could help Hull's Europa League claims - a top-four finish for the Gunners would see the cup-winner's place revert to Hull no matter the result on May 17.
But on-loan Spurs man Livermore was in no mood to settle for the status quo, and sent a low drive against the inside of a post with Szczesny hopelessly beaten.
Long failed to make a meaningful contact with Liam Rosenior's cross and was punished by a second Arsenal goal on the stroke of half-time.
Hull were incensed as Jelavic was not awarded a free-kick after Arteta's challenge - a borderline call - and when Arsenal countered quickly, Ramsey chested Giroud's cross down to Podolski who rifled home.
Cup hero Matty Fryatt replaced Long at half-time but could not get the better of Sagna and Szczesny from his first opportunity.
Nine minutes into the second half, Podolski make it three. Harper saved well with his foot from Ramsey's initial effort but could only present the German with a simple finish.
Jelavic's shot was deflected away for a corner, and from it the Croatian's header forced another, but Hull could not find the cutting edge.
Harper had a real let-off when he misread Rosenior's back-pass and hacked the ball against Giroud. The France striker chased down the loose ball but hit the bar from an acute angle.
Rosenior's cross eluded substitute Stephen Quinn, newly on for Jelavic, and at the other end Per Mertesacker almost diverted Cazorla's poor free-kick on goal.
Harper saved well from Ramsey before an increasingly rare Hull threat saw Huddlestone's shot tipped over by an unsighted Szczesny.
The 2,000 visiting fans in the crowd of 24,762 made their own entertainment by chanting the name of beleaguered Tottenham boss, and boyhood Arsenal fan, Tim Sherwood.
Fryatt stung Szczesny's palms from range but the match fizzled out in the closing stages, with Arsenal content with their winning margin.