Kaino was born on 6 April 1983 at Lyndon B. Johnson Medical Center in Faga'alu, located in the U.S. territory of American Samoa as the third of six children.

In 2012 it was announced that Kaino would be leaving the Blues for Japanese club Toyota Verblitz on a two-year deal, following the conclusion of the 2011 Rugby World Cup.

[5] On 4 October 2013, Kaino announced he had re-signed with New Zealand Rugby Union, North Harbour and Auckland Blues on a two-year contract.

Kaino made his All Blacks debut on 4 December 2004 when he started at blindside flanker against the Barbarians in an uncapped fixture at Twickenham Stadium in London.

Kaino returned to the All Blacks from his stint in Japan and during the 2014 three-test series against England, temporarily replaced incumbent number eight Kieran Read, who was being forced to sit out after suffering a relapse of concussion symptoms.

[14] Kaino returned to blindside flanker in the third test if the series following Read's recovery, pushing Liam Messam out of his starting place.

This season most notably included the 40-29 defeat to Ireland in Chicago where Kaino was featured out of position as lock, due to injury previously received by Brodie Retallick and Sam Whitelock against Australia.

Kaino recovered from a knee injury to be selected as a member of the All Blacks' 33-man squad for the 2017 Pasifika Challenge and three-test series against the touring British & Irish Lions team.

Becoming one of few players to play against the Lions in multiple tours, Kaino took part in the first test of the 2017 series on 24 June 2017 by starting at blindside flanker for his home crowd at Eden Park.

Kaino was unfortunately subbed off less than 30 minutes into the second test of the Lions series due to the red-carding of Blues teammate Sonny Bill Williams.

Following the drawn Lions series, Kaino was selected for the 2017 Rugby Championship but did not play in the competition for personal reasons, making his first ITM Cup appearance for Auckland in 7 years.

Kaino's absence from the Rugby Championship saw him lose his starting spot to Liam Squire and Vaea Fifita who spent the 2017 putting forward cases to make the number 6 jersey theirs.

Kaino started at number 8 in the All Blacks' 31-22 win over the Barbarians on the end-of-year tour but was subbed off with a posterior cruciate ligament injury in the 45th minute and replaced by Sam Cane.