Santner got his chance to represent New Zealand once Daniel Vettori decided to retire from the game. He is a like-for-like replacement of the veteran. Having played only 19 List A matches for Northern Districts, the selectors saw the potential in him and fast-tracked him to the national side. Santner was sent on the England tour to play a couple of practice games as some of the Kiwi players were absent due to their IPL commitments.
In only his first game on English soil, Santner impressed everyone, not with the ball, but with the bat. The youngster scored 27 and 94 in the two innings. He was part of the Test squad, but didn't get an opportunity. However, he made his way in the side during the ODI series. He played all 5 matches - picked up 7 wickets and scored 97 runs. Though New Zealand lost the series 3-2, Santner was one of the positives to have come out. He, along with Ish Sodhi, makes New Zealand a decent spin attack these days.
Santner's batting particularly dipped during the 2016-17 phase while his bowling hasn't been that effective either. Santner did start 2018 brightly though and the IPL selection by CSK boosted him further, only for an injury to rule him out for a major part of the year. Considered by many as the next Daniel Vettori, the legend himself has rated Santner highly and hopes that the all-rounder can end up as one of the country's finest cricketers. In the IPL, Santner mostly finds himself on the bench due to senior overseas stars who hog most of the foreign slots in the CSK team. He has proved his worth in his limited opportunities and could be a more regular starter in the years to come.