Nkomo, 78, was said to have died at Saint Anne’s hospital in Harare.
“We have lost our vice-president John Landa Nkomo, he was suffering for a long time with cancer,” said Mugabe.
“We have lost a real revolutionary, a fighter of freedom, a friend of the people, he will be dearly missed by all of us.”
Nkomo was appointed to one of the country’s two vice-presidencies under Mugabe in late 2009.
Responsible for overseeing financial, economic and environmental policy he was seen as loyal to Mugabe.
He “can be counted on to do Mugabe’s bidding”, a leaked US diplomatic cable dating from 2009 said.
His Ndebele roots made him useful in checking the opposition Movement for Democratic Change in Matabeleland, a western region where the MDC enjoys strong support.
While he was sometimes mooted as a successor to Mugabe, few believe he had a real shot at taking the top post.
His appointment was the culmination of a political journey that began in the early 1960s, when he joined the Zimbabwe African People’s Union, a pro independence movement, which later became part of Mugabe’s Zanu-PF.
The US embassy in Harare expressed its condolences, saying he played “an important role in shaping the course of Zimbabwean history”.
“Whether as a teacher, a politician, an advocate for Zimbabwe’s independence, or as a public servant, Vice President Nkomo was a patriot who dedicated his life to Zimbabwe’s sovereignty and prosperity,” the embassy said in a statement.
– AFP