But there was no independent confirmation, however, pictures circulated on social media appeared to show Saleh's body.
Yemen's former President Ali Abdullah Saleh addresses a rally held to mark the 35th anniversary of the establishment of his General People's Congress party.
Media channels in Iran, whose government backs the Houthis, and al-Arabiya, a Saudi channel, also announced Saleh's death.
Circumstances of his death remained unclear but some officials said rebels killed him as he tried to leave the capital Sanaa.
BBC World Service journalist Mai Noman said: "Saleh's death: shocking not just bec he ruled #Yemen for over 30yrs, he's been the key player in every major event even after being ousted".
For his part, Houthi leader Abdel Malek al-Houthi called on Saleh to end what he called "the sectarian strife" that he has instigated, and threatened to take action against his supporters militarily if he does not.
Yemen expert Nadwa Dawsari, of non-profit Project on Middle East Democracy, said Saleh's killing could have grave consequnces for the country.
A video by Yemen's Houthi rebels allegedly shows the slain body of the country's former leader Ali Abdullah Saleh.
Two of Mr Saleh's associates and a third official from the government of Yemen's internationally recognised president, Abed Rabbo Mansour Hadi, have confirmed the death.
The Houthis had branded him a traitor for allegedly striking a deal with Saudi Arabia.
The apparent shift in position came as Saleh's forces battled Houthi fighters in Hadda, a district in southern Sanaa where members of Saleh's family, including his nephew Tareq, live.
Yemen's war has killed more than 10,000 people since 2015, displaced more than two million people, and caused a cholera outbreak infecting almost one million people.
The fighting has killed dozens of people and wounded hundreds, according to the International Committee of the Red Cross, and raised concern of further casualties among civilians. Iran supports the Houthis but denies arming them.