England made 324 for seven, while Sri Lanka were bowled out at 202.
England beat Sri Lanka by 122 runs to win the fifth and final one-day international in Cardiff on Saturday.
Victory saw England take the series 3-0, with one tie and one no result.
England, sent into bat made 324 for seven, with Joe Root top-scoring with 93 and sharing a stand of 109 with Jos Buttler (70).
Sri Lanka, chasing a target of 325, were bowled out for 202 with more than seven overs to spare.