Jeremy Corbyn addressed thousands of supporters in London after finding out his name will be on the ballot paper in Labour's leadership contest.
Corbyn arrived at a fundraising event at the O2 Forum in Kentish Town, north London, on Tuesday evening, after a meeting with the party's ruling committee.
Supporters said Mr Corbyn was defiant and spoke about the upcoming party election.
Andy Gregg, from St Albans, said: "He reaffirmed our faith in the fact that change is possible. He astonished me by how resilient from the attacks from the establishment he was."
The shadow chancellor earned loud cheers as he launched an foul-mouthed attack on the MPs seeking to replace his friend Corbyn.
The MP for Pontypridd resigned as shadow work and pensions secretary last month in protest at Jeremy Corbyn's leadership.
I now realise that my earlier description of the NEC meeting - as an omni-shambles - was generous.