Chasing a modest target of 218, the home team made a rough weather of an easy chase before reaching the target in 47.5 overs as they made it to their third World Cup final.
However at one stage, it looked that Lankans will do a repeat act of their stupendous semi-final show versus England.
The winners were cruising at one stage with scoreboard reading 160 for one courtesy half centuries by Tillakaratne Dilshan and skipper Kumar Sangakkara. But New Zealand bounced back strongly dismissing three batsmen for nine runs as suddenly a match which looked thoroughly one-sided had some excitement still left.
But suddenly Daniel Vettori`s men were 30 runs short of trying to make a match of it. Finally, it was Samaraweera (23, 38 balls, 2x4) and Angelo Mathews (14, 18 balls, 1x4, 1x6) batting with a runner put an end to any improbable hopes that Black Caps harboured.
Mathews infact hit a big six off Southee over long on and followed it up with another one bounce four to calm the nerves as the target was reduced three. It was Samaraweera whose streaky four off McKay started victory celebrations in the Premadasa stands.
Earlier, neither Dilshan (73, 93 balls, 10x4, 1x6) nor Sangakkara (54, 79 balls, 7x4, 1x6) were flashy during their 120-run second wicket stand that lasted 25.2 overs after Upul Tharanga (30, 31 balls, 4x4, 1x6) was brilliantly caught by Jesse Ryder at point.
The duo ran well between the wickets but were equally adept in punishing anything that was pitched on their zone.
They used their feet well against the spinners. As they were cruising along the 100 runs for the second wicket came in 127 balls. However at 160 for one, suddenly Dilshan`s tired-looking flash gave Ryder a simple catch at point.
Skipper Vettori playing his last ODI then got one to pitch in line and trapped Mahela Jayawardene (1) leg-before.
Sangakkara, who had looked solid all this while suddenly had left-arm paceman Andy McKay dig one short at him. The ball climbed awkwardly onto the Lankan captain whose upper cut was easily caught at third man by Scott Styris.
From 160 for one, Lankans slumped to 169 for four losing three wickets for nine runs. Suddenly, the two new batsmen Samaraweera and Chamara Silva (13, 25 balls, 2x4) found it difficult to get going.
The Black Caps also found a spring in their strides as the fielders started cutting down on the singles and bowlers stuck to a disciplined line.
Silva however got couple of boundaries of Ryder before pressure got better of him. He played onto his stumps to give Tim Southee his third wicket as Sri Lanka suddenly looked down the barrel at 185 for five.
In the afternoon, it was the bowlers who helped Sri Lanka bundle out New Zealand for a modest 217 in 48.5 overs despite Scott Stryis`s fighting half-century.
Pace spearhead Lasith Malinga and spinner Ajantha Mendis, with three wickets each, were the wreckers-in-chief, while Muttiah Muralitharan finished with two salps as New Zealand`s innings lacked the thurst needed to power them to a challenging total.
Batting first after winning the toss, Styris struck 57 off 77 balls, an innings that was laced with five boundaries, before becoming Muralitharan`s final ODI victim.
The match at the Premadasa stadium is the veteran off-spinner`s final ODI on home soil.
Apart from Styris, Martin Guptill contributed 39 while Ross Taylor made 36.
New Zealand didn`t set the stage ablaze and preferred to play safe at the start. A run-rate of just about 4 by the time the mandatory powerplay ended was an indication of their approach.
But what must have hurt the Kiwis was Brendon McCullum`s early departure.
Continuing with his awful run with the bat, McCullum fell cheaply to Rangana Herath for 13. As McCullum positioned himself for a slog-sweap, a shot that brought him a six in the left-arm spinner`s previous over, Herath slipped in a quicker delivery that disturbed the off-stump.
Jesse Ryder joined Guptill and the two looked at ease until Muralitharan brought to an end the burly left-hander`s stay at the crease.
The veteran spinner, who came into this match with 13 wickets from eight matches and is playing in his last ODI on home soil, bowled a perfect off-break that took a thin edge off Ryder`s blade.
Returning for his second spell, Malinga then uprooted Guptill`s stump with a inswinging yorker to leave the New Zealander`s struggling at 84 for three in the 22nd over.
Guptill`s wicket was an important from Sri Lanka`s perspective as he has the ability to play the sheet anchor`s role to perfection. The gutsy right-hander was in his element till the slinger bowled that unplayable delivery to end his knock of 39 that included three hits to the fence.
With Guptill`s wicket, the pendulum swung Sri Lanka`s way, but the experienced Ross Taylor and Scott Styris forged a solid half-century partnership that paved the way for a competitive total.