Aki progressed to ITM Cup level with the Otago Razorbacks in 2012, making his debut in a match against local rivals Southland.
He was not named in any of the five New Zealand Super Rugby franchise's squads ahead of the 2014 Super Rugby season, however an injury crisis in the Highlanders front row saw him called into their squad to provide short-term cover.
He made the bench for the Highlanders clash with the Hurricanes on 16 May 2014, but remained an unused replacement.
Seiuli made his Super Rugby debut against the Chiefs in 2016 and made a further 4 appearances for the Highlanders.
He was included in the Highlander 2017 Super Rugby squad.
Seiuli featured in 14 of the Highlanders 16 Super Rugby matches and came off the bench against the British and Irish Lions.
Having missed the 2019 Super Rugby season due to an ACL injury, Seiuli returned to action for Otago in August.
In September 2019, he signed a two-year deal with Glasgow Warriors and join sthe club following Otago's 2019 ITM Cup campaign.
|2019 - present|
|2014 - 2019|