Career
Early Born in Tonga, Vainikolo's family moved to New Zealand in 1997 when he was 12. He moved through rugby age group levels in Auckland before moving to the Wellsford club in Northland in 2007. He made his debut in the 2007 Air New Zealand Cup, scoring five tries in just 10 matches to earn himself a Super Rugby contract.
He repeated the feat with another five tries in 2008.Vainikolo transferred to Otago to join many of his Highlanders teammates for the 2009 Air New Zealand Cup. On the heels of his success with Northland, Vainikolo was drafted into the Highlanders squad for the 2008 Super 14 season. While the team endured a difficult campaign, Vainikolo stood out as an offensive weapon, finishing third in the entire competition with six tries, including several of the highlight-reel variety.
In the 2009 Super 14 season, Vainikolo struggled to repeat his first-year success, scoring only two tries and coming into increased criticism for his defensive play, splitting starts with the more reliable Kendrick Lynn. In 2010, he started the season sharing playing time with James Paterson, but started the last seven games of the year and finished with five tries to co-lead the club along with Israel Dagg. On the conclusion of Tonga's participation at the 2011 Rugby World Cup, Vainikolo joined the Irish province Connacht for the 2011–2012 season.
Having missed the pre-season and the first two months of the RaboDirectPro12 season, Vainikolo struggled to establish himself in the starting XV. Gradually, as he has settled and his performances improved as his confidence grew, he established himself as a key component in the Connacht attack. He is most notable for his eagerness to get involved, frequently coming infield to make a key tackle or to help clear out a ruck. Exeter Chiefs announced on their official website on 9 May 2013 that Vainikolo would be joining the Chiefs on a two-year deal.
After his stint with the Chiefs, Vanikolo signed with Top 14 side Oyonnax. Vainikolo was selected in the Tongan World Cup squad on 8 August, and made his test debut on 13 August 2011 against Fiji in a 27–12 loss. At RWC 2011, his first World Cup outing was a starting place in Tonga's 25–20 loss to Canada, his second appearance came against Japan in which he scored Tonga's third try in a 31–18 group match.
Fetu'u was called into the Tongan 2012 IRB Pacific Nations Cup squad, which is being hosted by Japan and Fiji in June 2012. He scored two tries in the first match of the 2013 IRB Pacific Nations Cup, in which Tonga beat Japan 27–17 on 25 May 2013.