Vainikolo was born and raised in the small Tongan village of Ha’alalo. As the second youngest of 6 children, Vainikolo moved to New Zealand at the age of 12 and attended Marcellin College. In 2007 Vainikolo made his ITM Cup debut for the Northland and caught the attention of Super Rugby franchises with his try-scoring ability. The following year Vainikolo joined the Highlanders and was a stand out performer on the wing during his three years in Super Rugby.
In 2011 Vainikolo made the move north to play with Ireland based side Connacht in the Pro12 competition and was a lethal part of their attack. After two years as a regular starter for Connacht Vainikolo join Exeter Chiefs and helped them win the LV Cup in 2014. After a stint in the English Premiership, Vainikolo moved to France to play with Top 14 side Oyonnax and is now with Valence Romans.
Vainikolo has also enjoyed success on the International stage. As a Tongan International, he received his first cap in 2011 against Fiji and has since played 28 tests for the ‘Ikale Tahi. Shortly after his international debut Vainikolo was selected for the 2011 World Cup and was a part of the squad which upset finalists France in pool play. In 2015 Vainikolo was selected for his second World Cup and is currently the leading try scorer in Tongan test history with 17 tries.