The defeat means further misery for beleaguered Pakistan whose tour has been blighted by spot-fixing allegations.
Leeds: Andrew Strauss scored his fifth one-day century on Sunday to help steer England to a four-wicket win over Pakistan in the final over and take a 2-0 lead in the five-match series.
England's captain was dropped on 23 but went on to score 126, guiding his team to 295-6 after a vital second wicket partnership of 146 with Jonathan Trott (53).
"When you are chasing 290-odd, you need one guy to bat for the majority of the innings and thankfully, I stayed there and was backed up well by Jonathan Trott," Strauss said. "The boys then finished it off well at the end."
England required six runs off the final over bowled by Umar Gul and reached its target with three balls remaining. Tim Bresnan, who finished 10 not out, edged the penultimate ball over the wicketkeeper's head for four and then scrambled a single to mid-off.
The defeat means further misery for beleaguered Pakistan whose tour has been blighted by spot-fixing allegations. Three suspended players facing anti-corruption charges returned home on Friday.
Pakistan earlier exploited the sunny conditions and a flat batting pitch in compiling a challenging 294-8 from its 50 overs.
Opener Kamran Akmal hit 74 from just 72 deliveries while Stuart Broad claimed 4-81 from 10 expensive overs.
Set a demanding total, left-handed opener Strauss plotted a well-constructed innings that spanned 134 deliveries and included 10 boundaries and a six. He was finally lbw to Saeed Ajmal.
Strauss's fortune came with the score at 50-1 when he flicked pace bowler Shoaib Akhtar to Mohammed Irfan at short fine-leg, but the 7-feet-1 fielder spilled the chance.
Irfan also made several misfields and allowed 40 runs from his seven overs before being forced off early with cramp for the second straight match.
Strauss' best spell was three consecutive boundaries off Irfan to go to 95, including an edge through the vacant slip region, a square drive and a pull. Trott supported him well in another solid if not entertaining 71-ball innings.
Pakistan was given the perfect platform by openers Akmal and Mohammed Hafeez (43) with a stand of 122 amid unusually ill-disciplined bowling and fielding by England. Tim Bresnan's first three overs cost 25 runs as Akmal scored five boundaries in seven deliveries.
Paul Collingwood struck with his second ball, trapping Akmal lbw as he attempted a sweep to a ball that struck him in line of the off-stump. It was the first ball Akmal received from the medium-pacer and he exited after scoring 12 fours.
Asad Shafiq (50) and Mohammed Yousuf (46) helped to rebuild the Pakistan innings, after the openers departed, with a stand of 74.
England followed a 3-1 Test series win and a 2-0 Twenty20 series victory with a 24-run win at Durham in the first one-day international on Friday.