[4] Matai played rugby league for Mount Albert Grammar in the first XIII alongside Sonny Bill Williams and Thomas Leuluai.

[5] Matai's junior clubs were the Bay Roskill Vikings, Ponsonby Ponies and Richmond Rovers in the Auckland Rugby League.

[6][7] In 2005 Matai moved to another Queensland Cup side, but soon left the Wynnum Manly Seagulls after securing an NRL contract with their associate club, the Manly-Warringah Sea Eagles.

Matai joined the Manly-Warringah Sea Eagles from the Wynnum Manly Seagulls in 2005 after impressing during a strong pre season of training and trials at the Brookvale Oval.

On 14 October 2006, Matai made his test debut for New Zealand against Australia, playing at centre in the Kiwis 30–18 loss at Mt Smart Stadium.

Once Matai left the field, the Kangaroos ended-up winning the game 58-0 and giving New Zealand their worst ever defeat by Australia in a trans-Tasman test.

Matai kicked a conversion goal-attempt to convert Sika Manu's try, but he was placed on-report for a high tackle in the Kiwis 30–6 loss.

[18] Matai missed New Zealand's World Cup match with Papua New Guinea after being handed a one-match ban for a high tackle against Australia.

In Round 15, against the South Sydney Rabbitohs, Matai played in his 100th NRL career match and scored two tries in Manly's 26–25 win at Brookvale Oval.

On 2 October 2011, in Manly-Warringah's 2011 NRL Grand Final against the New Zealand Warriors, Matai played at centre in Manly's 24–10 victory.

Matai travelled to England with Manly for the 2012 World Club Challenge match against 2011 Super League champions Leeds Rhinos, playing at centre in the 26–12 loss at Headingley Stadium.

[30] In Week 1 of the 2012 finals series against minor premiers the Canterbury-Bankstown Bulldogs, Matai played his 150th NRL career match in Manly's 16–10 loss.

[33] Matai, who had already been suspended earlier in the season for a shoulder charge on South Sydney Rabbitohs prop George Burgess, was placed on report for inciting a melee but did not have to front the judiciary for a record 15th time.

[34] On 6 October 2013, in the Sea Eagles 2013 NRL Grand Final against the Sydney Roosters, Matai played at centre and scored a try in the second half in Manly's 26–18 loss.

In Round 25 against the Penrith Panthers, Matai played his 200th NRL career match in Manly's 26–25 win at Brookvale Oval.