 Tu'ungafasi represented New Zealand Under 20 in the 2012 IRB Junior World Championship in South Africa making 5 appearances and scoring 1 try.On 29 May 2016 he was selected in the All Blacks squad for a three-test series against Wales.Tu'ungafasi made his debut for New Zealand in the third test of the series, which was a 46-6 thrashing of Wales where Tu'ungafasi replaced Blues teammate Charlie Faumuina off the bench after 53 minutes.