 Tu'ungafasi started for the Blues in a historic 22-16 win over the touring British and Irish Lions in 2017, becoming a regular player for the All Blacks off the bench after Faumuina's departure at the end of the Lions series.This saw Tu'ungafasi score his first try for the All Blacks in the record 57-0 win over South Africa in the 2017 Rugby Championship and make worldwide headlines for bone-crushing tackles on Wallabies first-five Bernard Foley and replacement lock Lukhan Tui in the third Bledisloe Cup test of 2017, but it was unfortunately lost 23-18 after Tu'ungafasi conceded a 3-point penalty to winger Reece Hodge for illegally taking out a Wallaby with three minutes left.Tu'ungafasi made his first start for the All Blacks in the 31-22 win against the Barbarians on the 2017 end-of-year tour and was one of only two players to make an appearance for the All Blacks on every match of the end-of-year tour, alongside Lima Sopoaga.