New Zealand won the second one-day international by 21 runs to take the series despite a century by Sri Lanka’s Thisara Perera.
Having secured the opener by 45 runs in Tauranga, the Kiwis wrapped up the series by downing the Asians at the same venue on Saturday.
The Black Caps posted 319-7 thanks to a well-made 90 by Ross Taylor and a 77-ball knock of 87 from Colin Munro.
Both batsmen were run out as was Jimmy Neesham, who smashed five fours and three sixes in his 37-ball 64.
Skipper Lasith Malinga was the most successful of the Sri Lanka bowlers, returning figures of 2-45 from his 10 overs but Perera conceded 69 runs from seven overs.
However, the all-rounder made amends with a scintillating knock of 140 which contained eight fours and 13 sixes and threatened to get his side over the line after they slipped to 128-7.
However, it was not to be as the tourists were all out for 298 from 46.2 overs, with opener Danushka Gunathilaka making 71.
Spinner Ish Sodhi was the pick of the New Zealand bowlers with figures of 3-55 and Monday’s final ODI in Nelson is now the proverbial dead rubber.