Younis's 101, made out of a 167-run third-wicket stand with Yousuf (60), helped complete a two-wicket victory for the touring side which put them 2-0 up after three matches of the five-game series.
The contest at Southampton's Rosebowl, however, ended in unexpected drama when 20-year-old fast bowler Stuart Broad [ Images ] and Jon Lewis shared three wickets in the 47th and 48th overs to give England hope of a miraculous escape before Inzamam-ul-Haq [ Images ] steered his side home with seven balls left.
Chasing 272 to win, Inzamam completed the game by bludgeoning 44 off 33 balls.
Despite England's respectable total of 271 for nine - all the more creditable after Marcus Trescothick [ Images ] fell to the first ball of the game from Shoaib Akhtar [ Images ] -- they were still dominated in all departments but one -- fielding.
Pakistan's efforts in the deep were almost comical at times, but their bowling and batting was first-class.
Younis, whose only previous one-day international century came against Hong Kong, stood out after Pakistan slipped to 29 for two in reply.
Shoaib Malik [ Images ] fell to the sixth ball of the innings, slicing a wide delivery from Lewis to gully, while Mohammad Hafeez [ Images ] was run out by a direct hit from Andrew Strauss [ Images ].
England, however, lacked a wicket-taker to exploit those breakthroughs, although it would have taken something special to dislodge the man of the match. Younis made his 100 off 105 balls. He hit 13 fours and a six.
The right-hander took the game by the scruff of the neck, with Broad his main victim. Angry after an exchange of words with England's fielders, Younis smashed Broad for two consecutive fours then pulled the next ball for six to announce his intentions.
Younis, dropped on 38, was otherwise faultless until, having got to 101, he drove on the up at Broad and was caught at long-on.
Yousuf, who batted for a large part of his innings with a runner after straining a muscle, was then bowled by a classic off spinner from Jamie Dalrymple, leading to the unexpected drama of the final overs, when three wickets fell for nine runs. Broad took three for 57. Earlier Rana Naved-ul-Hasan took four for 57 for Pakistan.
England's innings began badly when Shoaib bowled Trescothick with an inswinging yorker off his pads with his opening delivery. They also looked vulnerable at 125 for four in the 25th over.
Strauss was England's shining light, with a fine 50 off 46 balls but, unlike Younis, he was not able to push on to a major score.
It was left to Paul Collingwood [ Images ] (61) and Dalrymple (62) to give England a fighting chance. They put on 101 for the fifth wicket but lacked the explosive strokeplay to set a truly formidable total.