Pakistan, who lost Friday’s opening game in Dubai by seven wickets, were set a victory target of 149 and were in trouble when debutant fast bowler Ajmal Shahzad grabbed two wickets in the first over.
Spinner Graeme Swann also claimed three wickets as Pakistan slipped to 78 for five but Razzaq showed no fear, carrying his team to victory with six balls to spare.
Earlier, England were indebted to Kevin Pietersen as they chalked up 148 for six after being put in to bat.
Pietersen followed up his 43 not out on Friday with a dynamic 40-ball 62 that included three sixes.
He and opener Jonathan Trott (39) shared a stand of 98 for the second wicket but seamer Yasir Arafat pegged England back by taking three for 32.
England leave for their tour of Bangladesh today while Pakistan’s next mission will be to defend their Twenty20 World Cup title in the Caribbean in April and May.
