Lomu was born in Auckland, New Zealand of Tongan descent. He grew up in South Auckland and attended Wesley College. While at Wesley and being coached by Chris Grinter, Lomu became a mobile loose forward for 5 years in the college's First XV.
It was in 1994 at the Hong Kong rugby sevens tournament that he started to attract attention.
At the age of 19 years and 45 days, Jonah Lomu became the youngest All Black test player as he debuted against France in 1994.
Lomu married South African Tanya Rutter in 1996, but in 1998 they separated.
At the 1998 Commonwealth Games in Kuala Lumpur he won a gold medal as part of the New Zealand rugby sevens team.
May 2003, the NZRFU announced that Lomu had been put on dialysis three times a week due to the recent deterioration in his kidney function and may eventually need a kidney transplant.
On August 21, 2003, Lomu married the Fiona Taylor on Waiheke Island.
At 1.96 metres tall Lomu is as tall as most locks, at 120 kilograms is as heavy as most prop forwards, yet being so big he is still able to cover the distance 100 metres in 10.8 seconds.