Kerr-Barlow began his professional rugby career in 2009 when he made his debut for Waikato at 18 years old. Kerr-Barlow was eventually signed to the Chiefs, making his debut for them in 2011 and became a regular starter for both teams.
Kerr-Barlow was first selected for the All Blacks to go on the end-of-year tour in 2012. Kerr-Barlow made his international debut in a 51-22 win over Scotland, replacing veteran Piri Weepu in his 69th test with 19 minutes to go. Kerr-Barlow also came off the bench to replace Aaron Smith in a win against Italy the following week. Kerr-Barlow cemented his spot as a regular back-up for Smith off the bench in 2013, replacing Smith off the bench eleven times that year. Kerr-Barlow also earned his first test start in 2013, starting against Japan on the end of year tour. Kerr-Barlow was subbed off with 12 minutes left and the All Blacks went on to win 54-6.
After coming on as a replacement, he scored his first two international tries in the quarter-final victory against France, which New Zealand won by 62-13. This marked a remarkable return from injury to play in the Rugby World Cup 2015. Kerr-Barlow's injury trouble in 2014 and 2015 was covered by the likes of Andy Ellis and Brad Weber before the World Cup started. The double that Kerr-Barlow scored against France were his only international tries in his career.
After good form continued in 2016, Kerr-Barlow continued playing for New Zealand, replacing TJ Perenara off the bench for the Rugby Championship. Kerr-Barlow earned his second career start against Italy on the end of year tour, leading the Haka against the Italians for his first and only time. Kerr-Barlow was released by New Zealand to play for the Māori All Blacks against the United States the week before, starting for them in Chicago. Kerr-Barlow was also released to play against the British & Irish Lions with the Māori All Blacks in Rotorua on 17 June 2017. Kerr-Barlow had a disappointing performance, being yellow carded in the 48th minute for a dangerous tackle.
Kerr-Barlow announced that he would leave New Zealand after the 2017 Rugby Championship to play for La Rochelle in France. Kerr-Barlow played his final game for the Chiefs following a quarter final 27-13 defeat to the Crusaders in Christchurch.
Kerr-Barlow was named in the 2017 Rugby Championship squad, coming off the bench in wins against Argentina and South Africa. Kerr-Barlow played his final two matches for New Zealand on the 2017 end-of-year tour, starting against a French XV, and led the Haka for his final appearance in a black jersey. Kerr-Barlow played the majority of the match before making way for All Blacks debutant Mitchell Drummond with ten minutes left.
On 15 March 2017, Kerr-Barlow traveled to France to sign for Top 14 side La Rochelle from the 2017-18 season.[2]
In August 2022, Kerr-Barlow announced he was willing to switch allegiances to the Wallabies to play for his country of birth, taking advantage of World Rugby's new eligibility rules.[3]
