Barrett has played at under-20 and Sevens levels for New Zealand before being called into the All Blacks' training squad in May 2012 and made his international debut as a replacement in the final test against Ireland in Hamilton, when he kicked nine points. He debuted for Taranaki in 2010, and debuted in Super Rugby with the Hurricanes in 2011. In 2016, he won the World Rugby Player of the Year award.
Barrett was born in New Plymouth to parents Robyn and Kevin Barrett. He grew up on a local farm in Pungarehu, a small town in South Taranaki near Opunake, with his seven siblings. He has four brothers and three sisters, with Kane a former Blues representative and Taranaki captain and current All Blacks, Scott and Jordie. Barrett spent a year in Ireland, when he was eight years old. He attended St Fiach's National School in Ballinacree, where he and his brother Kane learned how to play Gaelic football. He played for the Rahotu and Coastal Rugby clubs throughout his early childhood rugby, whilst he also represented Francis Douglas Memorial College in New Plymouth, where he excelled in its first XV.
Barrett came to the attention of national selectors at the age of 19, after he was selected in the New Zealand Sevens team for the final two legs of the 2010 IRB Sevens World Series in England and Scotland and debuted for Taranaki in the ITM Cup against Northland.
Barrett made his debut for Taranaki in the 2010 ITM Cup competition, coming on as a replacement against Northland. The then 19-year-old had made a huge impression in his opening season for the province, especially in his ability to attack the line and create space which saw him named most promising player of the year. Barrett soon enough caught the eyes of coaches, after a solid performance against Manawatu. Coming off the bench to score a 65-metre solo try that secured his side a bonus point win with 10 minutes to play. Barrett's try, his third of the season, helped Taranaki to their eighth win of the season, maintaining their position in the top four.
With his season over with Taranaki, it left Barrett with tough decisions to make on his Super Rugby future. Weighing up whether to take up a wider training group contract with the Hurricanes or look at other offers, including one from the Blues. Barrett decided to opt with the Hurricanes to become a Hurricanes wider squad member in 2011 after turning down the offer from the Blues. He was called up by the Hurricanes before the side's 2011 tour to South Africa where he saw time off the bench, earning his first four Hurricanes caps. He made his debut in a 50–47 win over the Cheetahs in Bloemfontein, a match that saw the Hurricanes prevail on full-time with a try to lock Jeremy Thrush that Barrett converted.
In his second season with the Taranaki squad for the 2011 ITM Cup, Barrett scored 90 points for the season, including an ITM Cup record after he kicked nine penalties in a 39–33 win over Bay of Plenty. With Barrett playing, Taranaki finished a respectable third placing in the ITM Cup and was instrumental in securing his side the Ranfurly Shield off Southland. Barrett was crowned Taranaki best back of the year for his efforts.
In 2012, Barrett began with his first Super Rugby match-day start with the Hurricanes against the Stormers. He produce a man of the match performance during a 39–26 loss. Barrett lead effectively with two try assists, one for second five Tim Bateman and another for reserve hooker Motu Matu'u that was latter disallowed by the television match official. He scored one himself and landed all of his six attempts at goal. Barrett also celebrated a record-setting display of goal kicking during the Hurricanes' 66–24 win over the Melbourne Rebels. It saw his 21 points brake several franchise records previously held by Jon Preston, including his 1997 mark of 152 points for the season. He landed all nine of his conversion attempts, eclipsing the previous mark of six shared by Christian Cullen, Willie Ripia and Jimmy Gopperth. It was only the second time the Hurricanes have scored nine tries in a match and their total of 66 bettered the 64 scored against Northern Transvaal in 1997.
Due to his international duties, Barrett appeared only four times in 2012 for Taranaki, recording a respectable 60 points. He began the season with a win over Bay of Plenty, whilst scoring a 70-meter intercept try and converting all his goals. Barrett was then released from New Zealand national coach Steve Hansen to start in his first run-on against Wellington since Taranaki's successful Ranfurly Shield defence against Tasman on September 1. He also featured in 2012 rugby semifinals, when Taranaki took on Canterbury. The match had to go into extra-time after a 27-all draw at full time.
In 2013, Barrett represented the Hurricanes in his third Super Rugby campaign and finished with 186 points for the year. He found his best form of the season playing majority in the number 10 position but was switched to fullback now and then throughout the season after he showed his versatility for the Hurricanes in the position that year. With his international commitments, Barrett was kept from running out for Taranaki. Although he did feature at the launch of the sides 2013 alternative rugby jersey revealing.
Barrett ended speculation concerning his future by signing a two-year contract extension with the Hurricanes in 2014. The then 23-year-old only signed a 12-month deal the previous year after reportedly almost joining the Blues. Along with Julian Savea, he started all sixteen matches for the Hurricanes and by early April, in the 2014 Super Rugby season, Barrett had already scored 100 points. He finished the season scoring 209 points.
In 2015, Barrett had a couple of injuries throughout the Hurricanes 2015 season. He first had a frustrating month of rehabilitation for a knee injury suffered against the Crusaders on 2 May after Barrett's scans revealed a grade-two tear of the medial collateral ligament (MCL) in his right knee. He had been ruled out of the Hurricanes' Super Rugby derby match against the Chiefs with a calf strain. Barrett returned to Hurricanes just in time for the 2015 Super Rugby final in which the Highlanders created an upset and heaped heartbreak on the Hurricanes with a 21–14 win in Wellington.
He returned after missing the 2013 and 2014 seasons for the province after featuring at first five-eighth against Otago in round three of the competition. His performance didn't go unnoticed after a break, from set play, saw him break the Otago line with ease, and speed, to find wing Jackson Ormond in support to take his pass for the opening try in the 12th minute. With three minutes left in the first half, he sized up his options perfectly again to slip a kick across field where right wing Codey Rei was waiting in clear space to secure the ball and score.
In 2016, Barrett scored the most individual points that season with 223, in addition he was the only player in the 2016 Super Rugby season to surpass 200 points. He was named man of the match in the Super Rugby final, scoring 15 points as the Hurricanes beat the Lions 20-3 to win their first title.
Barrett conceded his responsibility as goalkicker for the Hurricanes to his younger brother Jordie- the team's new fullback following his own leg injury. Barrett's younger brother scored more points than him in the season as a result. Despite good discipline in previous seasons, Barrett received the most cards of any player in 2017. Barrett received four yellow cards, including one against the Lions in the semi-final held in Johannesburg. Barrett was also shown a red card against the Waratahs in April, with three minutes to go in the game, due to being issued two yellow cards that same match after he was caught deliberately knocking the ball down from the opposition.
In June 2012, Barrett was named in the All Blacks squad for the Irish tour of New Zealand. Barrett's Test debut was a memorable one; the first five-eighth coming off the bench after 24 minutes and helping the All Blacks contribute 9 points to a record 60–0 win over the Irish. He went on to play five Tests in 2012.
Barrett returned to international rugby in 2013, being named in the All Blacks squad for the French tour of New Zealand. Barrett was a key player, playing in the historic 30–0 victory over France, scoring his first test try, which was subsequently voted International Rugby Players' Association's Try of the Year for 2013.
Barrett holds the world record for consecutive wins since his first test (19 wins from 19 tests).
In June 2014, Barrett featured in all of the 3-Tests against England starting on the bench, in the mid-year Test series. He played in the opening 2 Bledisloe Cup Test games against Australia starting from the bench in August.
In September 2014, Barrett then got an opportunity to start in the All Blacks No. 10 role for the first time in his All Black career playing against Argentina at McLean Park in Napier following an injury to Aaron Cruden. Despite having a tough night with the goal-kicking, kicking only one from five attempts, he produce a strong 55-minutes performance and being involved in setting-up the team's 3 tries. He was then sub off by Colin Slade in the 55th minute. The following week, he was benched for the home-game clash against South Africa and came on to replace Aaron Cruden in the 58th minute of the All Blacks 14–10 win over South Africa kicking a successful penalty goal attempt.
Following Aaron Cruden's boozy night out and off-field drama, Barrett got more opportunity to start in the All Blacks No. 10 (Fly Half) role, starting for the last 2 Tests of the Rugby Championship. He even guided the All Blacks to a 3-straight Rugby Championship Title in the All Blacks' 34–13 win over Argentina in La Plata and then he featured in the 25–27 loss to South Africa in Johannesburg. He finished the Rugby Championship with 30 points (6 Conversion Goals and 6 Penalty Goals) as 5th highest point-scorer (behind teammate Aaron Cruden with 37 points).
On 18 October 2014, despite Aaron Cruden returning to the team squad for the third Bledisloe Cup match in Brisbane, coach Steve Hansen selected Barrett to start at No. 10 for the team's clash against the Wallabies. He played for 72 minutes, kicking 3 goals from 4 attempts and produced a strong performance, before being replaced by Colin Slade. The All Blacks won the game 29–28.
Barrett was selected for the 2015 Rugby World Cup, starting in one fixture against Namibia, and coming off the bench to cover wing and fullback in the rest.
On 31 October 2015, Barrett scored the final try in the 2015 Rugby World Cup Final match against Australia, having been substituted on for the injured Nehe Milner-Skudder. Dan Carter converted his try to make the final score 34–17.
During the Wales tour to New Zealand, Barrett came off the bench in the second test after Aaron Cruden was injured, he scored 11 points in the second test which New Zealand won 36-22. Barrett started in the final test against Wales; he was praised heavily for his 26-point haul in a 46-6 demolition of a tired Wales side.
Due to his superb form for the Hurricanes and against Wales during their tour; Barrett supplanted an injury-plagued Aaron Cruden at fly-half for the 2016 Rugby Championship. He seemed to cement his position as New Zealand's first choice fly-half as New Zealand beat Australia by a record 42-8, away; he followed this with another 29-9 victory over Australia in round 2. Barrett only seemed to get better as the Rugby Championship continued as New Zealand comfortably beat Argentina 57-22 and South Africa 41-13, winning the Championship with two rounds to spare. Barrett finished as the highest point scorer of the tournament, scoring 81 points across the 6 matches played.
Barrett managed to convert his brother Scott's first test try in the All Blacks' 40-29 loss against Ireland in November, after Scott scored on debut.
Barrett won the award for World Rugby Player of The Year later in the year, beating teammate Dane Coles to the award and becoming the next All Blacks player after Dan Carter to win that award. Barrett's 95-meter individual try against France in New Zealand's final match for the year saw Barrett overtake Ben Smith as the second to highest try scorer in the All Blacks for the year, scoring 9 tries throughout the calendar year, having doubled his career total. Barrett finished behind winger Israel Dagg who scored 10 tries that year.
Barrett was selected for the All Blacks' 33-man squad to face Manu Samoa and the British and Irish Lions in 2017. His brothers Scott and fellow Hurricane Jordie were selected too. This meant the Barrett family were the first to have three siblings selected for the same All Blacks squad. Barrett scored 24 points including two tries in his 50th test match, against Samoa, which was also his brother Jordie's debut. Although Beauden and Jordie weren't on the pitch at the same time, Scott shared game time with both of them.
Test record overall: