[3] He made his debut during the second round of the tournament, taking charge of the Highlanders vs Crusaders clash on 21 February as a late call up for injured referee Chris Pollock.

After the 2023 Super Rugby Final he came under severe social media criticism which included death threats in which he posted a public statement against.

[8] On 18 July 2015 he made his international debut as an assistant referee, officiating in the first match of the 2015 World Rugby Pacific Nations Cup, Fiji vs Tonga.

In 2016, O'Keeffe made his Six Nations Championship debut on 7 February as assistant referee in the Ireland vs Wales match, then Italy vs England the following weekend.

[9] On 11 June 2016, O'Keeffe made his international refereeing debut, taking charge of the historic match between Samoa and Georgia which ended in a 19 all draw.

[10] He was widely praised for his handling in the final pool match of the tournament; the historic 28-21 win by host nations Japan over Scotland.

O'Keeffe is now recognised as one of the top match officials globally and was selected to referee the second test of the British and Irish Lions tour of South Africa in 2021 and the 2023 Rugby World Cup in France.