Anthony Gerrard struck the only goal to ensure an unhappy first return to the KC Stadium for former Hull manager Phil Brown whose winless run in charge of rockbottom Preston was extended to six matches.
Brown, placed on gardening leave as Hull boss in March 2010 and eventually replaced by Nigel Pearson in the summer, was installed at Preston in January, but the Lilywhites' last league win was on December 11 and they remain in freefall at the foot of the npower Championship table.
Hull, who extended their own unbeaten league run to seven matches, took a deserved lead through Gerrard's towering header on the stroke of half-time and were troubled only in the closing stages by a Preston side bereft of confidence.
The Tigers have lost only one of their last 16 games since a 1-0 home defeat to Humber rivals Scunthorpe in November, but Brown's side have won only one of their last 15 league games and remain 10 points adrift of safety.
Tunisia international Tijani Belaid made his first start for Hull and was quickly into the action when his early angled drive was blocked by Preston defender Sean St Ledger.
Hull had already gone close to taking a second-minute lead through Aaron Mclean's volley and went on to dominate possession without creating any clearcut openings.
Preston's first chance fell to defender Leon Cort, who headed Adam Barton's corner wide in the 18th minute, while Hull midfielder Robert Koren forced Preston goalkeeper Iain Turner into a fine sprawling save with his powerful shot a minute later.
Turner pulled off another commendable save 10 minutes before the break to deny Belaid from inside the area and Hull defender Corry Evans saw his 20-yard effort blocked by Cort.
Tigers midfielder Koren skewed a long-range drive off target, but Hull took a deserved lead just before half-time when Gerrard rose to plant a downward header beyond Turner from Andy Dawson's corner.
Koren powered a 30-yard volley just wide seven minutes into the second half and although Eddie Johnson lashed in a 25-yard effort, Hull threatened to extend their lead twice in quick succession.
Matty Fryatt's shot from inside the area was blocked by the over-worked Cort and Turner did well to hold on to Cameron Stewart's stinging drive following Dawson's quick free-kick.
Cort forced Hull goalkeeper Brad Guzan into a rare save in the 71st minute with another header before Gerrard diverted Barry Nicholson's shot and Dawson got in the way of a Billy Jones header.
Preston enjoyed their best spell midway through the second period, with Nicholson, a 69th-minute replacement for Darel Russell, providing them with much-needed guile.
But Stewart fired just wide for Hull before making way for substitute Jamie Devitt and Mclean's shot was blocked by Cort as the home side finished on top and despite two late scares when Preston substitute Paul Hayes and defender David Gray volleyed over the crossbar, climbed up to ninth place in the table.