Stuart Green's outstanding first-half strike edged Hull closer to safety and increased bottom-placed Crewe's relegation fears.
The midfielder sent a delightful right-foot volley into the top corner after 16 minutes from Stuart Elliott's left-wing cross in Hull's first attack of the game.
Green's third goal of the season lit up a dull affair during which neither side displayed much quality but Hull ultimately held on comfortably for another vital victory.
Peter Taylor's men recorded a morale-boosting 1-0 home win against Plymouth last weekend but they began sluggishly against the struggling Railwaymen.
Crewe arrived at the KC Stadium having won just once on their travels this season, but came close to opening the scoring after four minutes when Steve Jones fired a 20-yard volley narrowly wide.
Crewe began to dominate and their slick passing began to embarrass the below-par Tigers.
For all Crewe's neat approach play, however, they failed to penetrate and were hit with a classic sucker-punch after 16 minutes as Hull opened the scoring with their first attack of the game.
Jon Parkin displayed delightful footwork to control goalkeeper Boaz Myhill's long clearance and lay the ball out to Elliott on the left flank.
Craig Fagan, restored to the starting line-up after coming off the bench to score the winner against Plymouth last week, arrived at the far post to meet Elliott's delivery.
When the ball skimmed off his head and fell to Green on the right-hand side of the penalty box, the Hull midfielder struck a delightful shot into the top corner from 14 yards.
It was an outstanding third goal of the season for Green and the in-form Parkin wasted no time attempting to claim an all-important second.
The powerful striker has rapidly acclimatised to life in the Championship following his £150,000 January move from League Two strugglers Macclesfield, with five goals in his first 10 appearances.
He almost claimed his 11th shortly after the half hour mark when he collected possession on the edge of the box and hit a thunderous left-effort which warmed Ross Turnbull's hands.
Hull almost made it 2-0 on 38 minutes when Leon Cort's header was cleared off the line by Crewe midfielder Lee Bell.
Moments later Fagan found himself unmarked at the back post but fired over when he should have at least hit the target.
The Railwaymen remained dangerous on the break and could have been level when Bell engineered himself a shooting chance from 12 yards but Damien Delaney produced a vital block to avert the danger.
There was precious little quality on show from either side as the game wore on, with noteworthy goalscoring chances conspicuous by their absence.
But Parkin remained a threat and was desperately unlucky not to claim a deserved goal in the closing stages.
The giant striker cracked a shot against the bar and substitute Billy Paynter could only blast the rebound over.
Teams
Hull Myhill, Wiseman, Cort, Delaney, Rogers, Green, Andrews,Noble (Paynter 66), Elliott (Ellison 64), Parkin,Fagan (Duffy 74).
Subs Not Used: Duke, Thelwell.
Booked: Noble.
Goals: Green 16.
Crewe Turnbull, Otsemobor, Foster, Bougherra, Billy Jones,Bell, Lunt, Grant (McCready 82), Steve Jones,Rodgers (Vaughan 59), Taylor (Higdon 66).
Subs Not Used: Tomlinson, Johnson.
Att: 21,163
Ref: T Kettle (Berkshire).