Opener Salman Butt hit an attractive century to lift Pakistan to 329-9 in 50 overs in the fifth and final day-night international at National Stadium here on Saturday.
The 23-year-old left-hander scored 136 for his sixth one-day hundred, second in the series, and added a record 179 runs for the second wicket with Younis Khan (69) after Pakistan won the toss and decided to bat.
Pakistan, leading the five-match series 4-0, once again had a field day as the home batsmen piled misery on Bangladeshi bowlers who failed to stop the run spree.
Captain Shoaib Malik (27) and Misbah-ul Haq (35) added a quickfire 52 for the sixth wicket to give the final touches to the innings after Butt built the platform.
Butt, who hit his previous highest one-day score of 132 in the third match in Lahore on Sunday, hit 14 boundaries and a six during his punishing 124-ball knock.
Pakistan raced to 28 by the fifth over before losing Kamran Akmal, caught in the slips off paceman Mashrafe Mortaza for 10. Akmal hit two boundaries.
Butt and Younis steadied the innings, as both hit some delightful shots. Butt reached his hundred in as many balls, hitting nine fours and a six off spinner Shakib Al Hasan.
Younis, who returned to the squad as one of three changes, miscued a pull off Shahadat Hossain to be caught by a running Farhad Reza at square-leg. Younis hit four boundaries and a six during his 80-ball knock.
His partnership with Butt is a new Pakistan record against Bangladesh, beating the 123-run second wicket stand between Saeed Anwar and Rameez Raja at Colombo in 1997.
Butt too miscued a drive off spinner Abdul Razzak in the 38th over. Mohammad Yousuf fell for 22 and Shahid Afridi managed just four.
Pakistan lost four wickets in the final five overs as debutant Naumanullah made five while Wahab Riaz scored three.
Mortaza bowled accurately to finish with 4-65.