Jeremy Corbyn said disabled people and those on social security had been "demonised" by some politicians as he slated the Government's record over help for society's least fortunate.
Mr Corbyn, at the Labour Party's launch to develop policies to fight discrimination and promote disability equality, said some disabled people had faced "horrifying" hate crime since Brexit.
The Labour leader said: "Some politicians have sought to legitimise cuts, demonising people with disabilities as scroungers and shirkers - remember that language that was used in the past?
"We will never use that language. It is out of court, unacceptable, and should be unacceptable in any kind of decent civilised society.
"And they have whipped up hatred towards disabled people.
"The hate crime that has grown particularly since the Brexit referendum has been horrifying.
"Horrifying in its racism, horrifying in its misogyny, horrifying in its homophobia, horrifying in its attacks on people with disabilities across the country."
The event, attended by 50 disabled people, heard they were now being "vilified" as "skivers" and the "undeserving poor".
But half of all people in poverty in the UK are disabled or live in a household with a disabled person, which Mr Corbyn said was a "shocking" indictment of the system.
He cited a United Nations report published on Tuesday which said the UK Government's austerity welfare reforms have led to "grave and systematic violations" of disabled people's rights.
The work and pensions secretary, Damian Green, dismissed the report as "patronising and offensive".
But the following day, the UK's highest court, the Supreme Court, ruled a spina bifida sufferer and the family of a teenager with severe disabilities had suffered "unlawful disability discrimination" over the housing benefit cap, or Bedroom Tax.
Paul Rutherford, 59, and wife Sue, 60, from Clunderwen, Pembrokeshire, who care for their profoundly disabled grandson Warren, 17, won their cases when judges dismissed the Government's appeal against an earlier ruling.
Mr Corbyn paid tribute to Mr Rutherford, who sat beside him at the event at Unison offices in Manchester.
He said: "The actions he took have changed the lives of thousands and thousands of people.
"Disabled people have been hardest hit by austerity.
"The Labour Party under my leadership wants to break from this failed austerity project and transform our social security system based on the principles of dignity, independence and support.
"By putting equality at the heart of our policies we can put Britain on the path to becoming an equal society for all."
Mr Corbyn said Labour in government would scrap "punitive" sanctions and the Bedroom Tax.
Labour's Disability Equality Roadshow, headed by Debbie Abrahams, Shadow Secretary of State for Work and Pensions, will go nationwide over the coming months.
Ms Abrahams, MP for Oldham East and Saddleworth, said: "This engagement process will take the first steps in developing policies which can tackle the structural issues affecting deaf and disabled people and their carers across the UK, as well as the challenges we all face in building a fairer, more equal society.
"It is part of Labour's commitment to transform our social security system, ensuring that, like our NHS, it is there for us all in our time of need."