The result also eliminated Australia from the tournament and Pakistan and West Indies will fight out for the second semifinal spot with India having already qualified for the last-four stage from Group 2.
Batting first, Pakistan scored a commanding 190 for five with Shehzad (111 not out) hitting his maiden T20 International century which was laced with 10 boundaries and five sixes from 62 deliveries.
In reply, it was yet another listless show from Bangladesh as they could score only 140 for seven as they lost their fourth successive match (including last game in the qualifying round) on trot.
Umar Gul (3/30) and Shahid Afridi (1/21) kept the Bangladeshi batsmen under wraps as the home side never looked like putting up a decent fight.
The match belonged to 22-year-old Shehzad, touted as the 'Next Big Thing in Pakistan cricket after Umar Akmal. He was off the blocks in a flash as he blasted the listless Bangladeshi bowling attack with a wide array of strokes on both sides of the wicket.