Pakistan were bowled out for 110 in 25.3 overs at Gaddafi Stadium. Sri Lanka completed the chase at 114 for two in 18.1 overs, according to the scoreboards.
Kamindu Mendis finished unbeaten on 62. Dunya News also reported that Dilshan Madushanka took five wickets for 34 runs.
Pakistan had already qualified. The two teams are therefore scheduled to meet in the final in Lahore on 31 October, with England eliminated from the title race.