[3] After his last year at New Plymouth Boys', O'Neill was enrolled into the 23-man New Zealand Secondary Schools team for a two-match international series in Auckland against Samoa and Australia.
[8] A week out, O'Neill snapped his achilles tendon and would require surgery after suffering a 42–10 defeat in a qualifying match against Waikato in Te Awamutu.
[10] His performance at premier club level saw him rejoin the Taranaki squad for their upcoming season after head coach Colin Cooper named his inclusion during the pre-season side announcement.
[17] O'Neill gained selection honours with the Canterbury-based side the Crusaders, on 31 January during their pre-season opener against the Hurricanes ahead of the 2018 Super Rugby season.
[22] Following his 2018 provincial campaign, O'Neill was called up into the wider All Blacks squad to prepare for the Japanese leg of the 2018 end of year tour without making a Super Rugby debut.
[23] O'Neill's versatility, being able to play both sides of the scrum in the prop position, caught the attention of the Chiefs selectors and was named in the franchises squad for their 2019 Super Rugby season.