Aki was born in the Auckland suburb of Otahuhu. He was a student at Manurewa High School in the city, where he played for the school's rugby team.
He took a year out from pursuing a professional rugby career in 2011 when he worked as a bank teller at Westpac to earn the money for his young family.
Aki was involved with the Chiefs wider training group in 2012. On the back of a superb ITM Cup season for Counties Manukau, he earned his first Super Rugby contract.
He was named the Counties Manukau Steelers Player of the Year and was awarded Player’s Player of the Year by his teammates. After 2 seasons and 25 appearances for the Chiefs, Aki left the Waikato-based side and moved to Irish side Connacht for the 2014/15 season.
In May 2016, he was recognized with the Players' Player of the Year honour at the Pro12 end of year awards ceremony.
After 47 appearances for Connacht, the charismatic centre signed a contract extension that would see him with the club until at least 2020.
In May 2017, after being originally announced in the Barbarians squad, Aki underwent surgery on an ongoing shoulder injury and missed out on a chance to get a taste for international rugby.
He returned in time for the start of the Pro 14 season and featured in all 6 of Connacht's opening fixtures.
In October 2017, he was named as one of four uncapped players in the Ireland squad for the November Tests against South Africa, Fiji and Argentina. He made his test debut for Ireland in a 38-3 victory over South Africa in Dublin on 11 November, 2017.
Aki qualified for Ireland having completed the required three years of residency for his adopted country after joining club side Connacht from the Chiefs in 2014.
He started at inside-centre for Ireland in all five matches that led to winning the Six Nations grand slam in 2018, and scored his first international try against Italy in the 2018 Six Nations in a 56-19 win for Ireland.
Aki earned 10 of his test caps in the Six Nations (2018 and 2019) and scored two tries in these 10 appearances.
He was selected for the 2019 RWC training squad in May of that year already with 17 appearances under his belt.
He finished the tournament with 23 caps and four tries scored.
In November 2019, the IRFU and Connacht Rugby confirmed that Aki signed a three-year contract extension that will keep him at the Sportsground up to the end of the 2022/23 season.
He was then named for the 2020 Six Nations Ireland squad with 23 caps to his name.
As of June 2020, Aki is one appearance shy of recording a century of caps for Connacht since his debut in 2014.
In May 2021, Aki was selected for the 2021 British and Irish Lions for the first time.
KK May 2021
|2014 - present|
|2017 - present|
|British & Irish Lions
|2021 - present|
|2013 - 2014|