Success in local club rugby saw Seiuli earn a spot in the Otago squad for the 2012 ITM Cup. After debuting in a match against local rivals in week 3 of the competition, he went on to play 7 times throughout the year as the Razorbacks reached the Championship final before being thrashed 41-16 by. He once again featured 7 times in 2013, with every appearance from the replacements bench before becoming much more of a regular in 2014. Injury to fellow loosehead Craig Millar meant that he started all 10 of Otago's games in what proved to be a difficult year which ended up with them finishing in 6th place on the championship log and missing out on the playoffs completely. 2015 brought about an upturn in Otago's form with a 3rd place log finish and an appearance in the Championship semi-finals before being downed 34-14 by, however Millar's return from injury meant that Seiuli found himself once again playing largely from the replacements bench, making just 2 starts from 10 appearances. It was a pattern which continued through 2016 Seiuli starting 3 games in the number 1 jersey to Millar's 9 as the men from Dunedin topped the Championship log before surprisingly losing out at home to in the final which consigned them to another season of championship rugby in 2017.
Super Rugby
Seiuli 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 set-up to provide short-term cover. He made the bench for the Highlanders clash with the on 16 May 2014, but remained an unused replacement and in the end didn't make any appearances during the year. He once again found himself in the Super Rugby wilderness in 2015 before injuries once again provided him with an opportunity in 2016. A season-ending injury suffered by Brendon Edmonds in April 2016 saw Seiuli brought in as back up to Daniel Lienert-Brown and Craig Millar. He finally made his Super Rugby debut in an impressive 26-13 victory over the in Hamilton on 7 May 2016 and went on to play 7 times in total during the year as his side reached the tournament semi-finals before going down to the in Johannesburg. Tony Brown replaced the bound Jamie Joseph as Highlanders head-coach ahead of the 2017 Super Rugby season and having worked with Seiuli before at provincial level, he saw fit to promote him to the franchise's senior squad ahead of his first campaign in charge.
