Guptill smacked a whirlwind 93 from just 30 balls in an innings that consisted 9 fours and 8 sixes.
Martin Guptill broke Brendon McCullums New Zealand record of fastest fifty off 18 balls. Guptill also scored the second fastest fifty in ODI cricket after equalling the likes of Kusal Perera and former Sri Lankan legend Sanath Jayasuriya.
He missed the record for fastest fifty which is held by South Africas AB de Villiers.
Guptill smacked a whirlwind 93 from just 30 balls in an innings that consisted 9 fours and 8 sixes as New Zealand chased down Sri Lankas total of 117 runs.
Batting alongside Tom Latham, 50 balls was all the duo took to knock off the 118 run target.
Earlier, Sri Lanka were bundled out for 117 in the 28th over after batting first against New Zealand in Hagley Oval.
Nuwan Kulasekara top scored with 19 runs.
Matt Henry, the chief destroyer when New Zealand won the first ODI by seven wickets, took four for 33.
Mitchell McClenaghan took three for 32.