Lomu, who scored 37 tries in 63 Tests for New Zealand during 1994 and 2002, suffered health problems since his retirement, undergoing a kidney transplant in 2004 and receiving dialysis treatment for the past decade.
Former All Blacks doctor John Mayhew confirmed the news.
“I can confirm that Jonah Lomu died this morning. It was totally unexpected, Jonah and his family arrived back from the United Kingdom last night,” he said.
New Zealand rugby chief Steve Tew added: “Jonah was a legend of our game and loved by his many fans both here and around the world.
“We’re lost for words and our heartfelt sympathies go out to Jonah’s family.”
Lomu had recently travelled to England for the Rugby World Cup, during which he was a spokesperson for Heineken.
Marauding winger Lomu famously destroyed England in the semi-final of the 1995 World Cup and provided one of the sports most iconic images when he steamrolled Mike Catt.
He scored four tries against England as the All Blacks won 45-29 in that last-four tussle and seven in total at the tournament, although New Zealand missed out in the final as Francois Pienaar’s South Africa prevailed.