England were put into bat for the first time in the series by Sri Lanka and made 324-9 from their 50 overs, with Joe Root, who made 93, Jos Buttler, who made 70, and James Vince, who made 51, all making half-centuries for the hosts.
Sri Lanka in reply never got going and lost wickets at regular intervals with only Dinesh Chandimal holidng any resistance making 53 as England bowled Sri Lanka out for 202.
David Willey took four wickets and Liam Plunkett took three wickets to be the main wicket takers for England as they won the series 3-0.
At the toss, Sri Lankan captain Angelo Matthews won it and chose to bowl first, for the first time in the series, as his team looked to salvage some pride.
Roy and Vince gave England a solid platform
England's innings got off to a good start with openers Jason Roy, who made a match-winning hundred in the last game and Vince, who replaced Alex Hales for the game, taking their partnership passed fifty.
The pair were going along well until Roy, who tried to go for a big shot off the bowling of Suranga Lakmal, mistimed it and was caught in the deep for 34.
The wicket of Roy brought Root to the crease to join Vince and the pair went about building another partnership. Vince passed his maiden ODI fifty before falling not too long after though for 51 of the bowling of Danushka Gunathilaka to leave the score on 108 for two.
England captain Eoin Morgan came in at number four and he looked to move the score along and he was doing just that before he just like Roy went for one to many big shots and fell for 20 from 18 balls of the bowling of Gunathilaka.
Johnny Bairstow came in next and he and Root again started to built another decent partnership. During this partnership, Root made his way past another half century and held the key to the rest of the innings for England.
Bairstow though couldn't stay with him as he fell for 22 of the bowling of Gunathilaka who got his third wicket of the innings to leave the score on 182-4.
Buttler and Root propel England to 324
The wicket of Bairstow though brought Buttler to the crease, who has a good record against Sri Lanka, and he showed it once again. Buttler made a rapid half-century for England as he went on the attack and put on 109 with Root for the fifth wicket.
Buttler was finally out for 70 off 45 balls, falling to Chaminda Bandara, but he had done his job well to get England up to a good score. Root kept going but in the final over of the innings he fell for 93 when Nuwan Pradeep bowled him with a slower ball.
Plunkett then came in and hit a couple of boundaries before being run out. England finished their 50 overs on 324 for seven.
England bowlers put the squeeze on Sri Lanka with early wickets
In reply, Sri Lanka's innings got off to a poor start when Kusal Perera was trapped LBW by Willey for six to leave the score on nine for one after four overs.
Kusal Mendis came in at number three and he and Gunathilaka started to put on a good partnership before Mendis was run out for 22 when the partnership reached 47. Bairstow was the man to get the breakthrough for England as he produced a great throw to cause the runout.
England didn't have to wait long for their third wicket either as Gunathilaka was out LBW to Plunkett for 48, to leave Sri Lanka on 83 for three and in a spot of bother.
Matthews came in at number five and just as he started to unleash some big shots, Plunkett responded for England with a fantastic yorker to bowl the Sri Lankan captain for 13. Upul Tharanga in at number six, was out first ball when Adil Rashid bowled him with a beautifully flighted delivery to leave Sri Lanka on 106-5.
Dasun Shanaka came in at number seven and he and Chandimal started to build a partnership before Shanaka fell for 22 of the bowling of Rashid. Seekkuge Prasanna then came in and couldn't get going as he was out for five of the bowling of Plunkett, who took his third wicket of the innings.
Chandimal made a half-century but Willey and Plunkett finish off the Sri Lanka tail
Chandimal continued on though and got his fourth half-century in a row in the series to show some fight for Sri Lanka. The problem though was that he kept losing his partner at the other end as Lakmal fell for 10 of the bowling of Willey.
Chandimal, therefore, had no choice but to go for it but that was his downfall as Willey bowled him for 53 to leave Sri Lanka nine down for 195.
England didn't take long to get the final wicket of the innings as Nuwan Pradeep was out for seven of the bowling of Willey, who finished with four wickets, as England bowled Sri Lanka out for 202 to win the match by 122 runs.