Sri Lanka piled up their highest one-day total against Pakistan of 368-4 after electing to bat in the fifth and final match in Hambantota on Sunday.
Left-handed opener Kusal Perera hit 116, sharing a first-wicket stand of 164 with Tillakaratne Dilshan, who completed 10,000 one-day runs during his innings of 62.
Skipper Angelo Mathews hammered an unbeaten 70 and Milinda Siriwardana plundered 52 not out off 26 balls as Sri Lanka surpassed their previous best against Pakistan of 349-9 in Singapore in 1996.
Sri Lanka are looking for a consolation win with Pakistan already 3-1 ahead in the series.