Now 29, Lomu has won 63 caps for New Zealand and scored 37 tries, making his first major impact on world rugby with a series of rampaging performances at the 1995 World Cup.
He will begin training with his new club in June, ahead of the 2005-06 National Provincial Championship beginning in August.
"I have been waiting for the chance to play again," said Lomu.
"I've got my ultimate dream and a plan to get there. Getting out on the field, that's goal number one and I'm really pleased to be doing that with Harbour."
North Harbour chief executive Noel Coom enthused: "A player of his quality and stature can only strengthen and positively add to our team - we can't wait for the season to begin."
Lomu was spending eight hours daily on dialysis after seven years of kidney problems came to a head, leaving his sporting future in the balance.
However he had a successful transplant operation in July 2004 and his health has since dramatically improved.
Lomu will make his rugby return in former England captain Martin Johnson's farewell match at Twickenham on June 4, however it will be back home that his competitive comeback will be seen.
When Johnson was leading England to their World Cup glory in 2003, Lomu, because of his illness, was a frustrated spectator.
However he harbours hopes of reviving his international career and added: "North Harbour offers a great team environment, it also has the added benefit of allowing me to remain in Auckland.
"It's the best of all worlds for me right now."
By signing with North Harbour, Lomu could return to Super 12 action with the Auckland Blues, the team with which he won titles in 1996 and 1997.
And Lomu has been held up as an example for every player in New Zealand by Harbour coach Allan Pollock.
"Not only does Jonah have speed, strength and great skills on offer but his desire and focus will impact the whole union," said Pollock.
Pollock referred to Lomu's Twickenham date as taking an "all-or-nothing approach to his comeback".
He added: "Choosing to play his first game at one of the most high profile matches this year is a huge call."
However, Lomu's doctor does not feel there is any risk attached.
John Mayhew confirmed: "Jonah's ready for action.
"He feels the best he has for years and we've all got something to look forward to on his return to rugby."
Lomu made his New Zealand debut aged 19 years and 45 days.
He played 28 National Provincial Championship games for Counties-Manukau between 1994 and 1998 and turned out 21 times for Wellington after signing for them in 2000.
Both of those provinces and Auckland were also in the race to sign him this time, but Harbour won the race.