[3] His father Kevin 'Smiley' Barrett was an uncompromising loose forward for Taranaki, playing 167 games for the amber and blacks.

[5] Barrett was a member of the New Zealand Under 20 team which participated in the 2016 World Rugby Under 20 Championship in England where he made 3 appearances in total scoring 52 points including one try.

[13] After being selected for New Zealand and continuing his form for the Hurricanes, Barrett was released to play against the British & Irish Lions midweek match.

[15] Whilst an apprentice in the New Zealand national team during their northern hemisphere tour, Barrett signed with Taranaki for 2017.

In June 2017, Barrett was one of three uncapped backs named in the All Blacks' 33-man squad for the Pasifika Challenge against Samoa and the three-test series against the touring British & Irish Lions 2017 team, along with brothers Beauden and Scott.

In what was brother Beauden's 50th test, Barrett made his international debut in the 78–0 against Samoa on 16 June 2017, replacing All Blacks captain Ben Smith in the 63rd minute.

Barrett was one of two debutants that day, with Hurricanes team-mate Vaea Fifita replacing veteran loose forward Jerome Kaino off the bench.

Barrett was initially named in the 2017 Rugby Championship squad for but was ruled out for the rest of the year after requiring shoulder surgery.

He scored the second and third two tries of his international career and played the full 80 minutes of the test, which was a 26–13 win, claiming the series for the All Blacks.

Barrett missed another test in the Rugby Championship, with his Hurricanes team-mate, Nehe Milner-Skudder, earning a re-call for New Zealand after a long period of time being injured.

[19] He was then bought back into the starting lineup, at fullback, for the first test against South Africa at Westpac Stadium, on 15 September 2018.

[23] On 8 December 2024, he made his debut for the club scoring a try from the bench in the Champions Cup as his side went on to beat Bristol Bears 35–12 at Ashton Gate.