Shadow work and pensions secretary Liam Byrne will tell the Labour conference that Atos is getting too much wrong and should be sacked immediately.
He will also commit Labour to making disability hate crime a specific offence amid fears people are being let down by the criminal justice system.
French-run Atos has come under heavy fire for its handling of work capability assessments, which are used to gauge eligibility for Employment and Support Allowance (ESA) and Incapacity Benefit and has been ordered by ministers to improve.
Labour said too many mistakes were still being made - with almost two in five assessments being appealed against and 42% of those appeals upheld, costing courts and tribunals around £20 million a year.
Backlogs meant 35,000 claimants were waiting longer than 13 weeks for a decision, the numbers sent home unseen were routinely in breach of the target and the Commons spending watchdog said people were being caused "considerable distress", it said.
But Mr Byrne will tell the conference: "I say to David Cameron, Atos are a disgrace, you should sack them and sack them now."
Outlining a package of measures to help disabled people, he will say that Labour "will change the law so hate crime against disabled people is treated like every other hate crime".
Earlier this year, police, prosecution and probation inspectorates warned victims of disability hate crime were being let down and attacks not properly recorded - partly because it was not clearly defined in law.
It followed high-profile cases such as that of Fiona Pilkington who ended years of torment by killing herself and her disabled daughter.
Labour said it would extend aggravated offences in the Crime and Disorder Act 1998 to include where hostility is demonstrated towards people on the grounds of disability as well as making "stirring up hatred" against disabled people an offence.
Such crimes would be "properly recorded" on people's criminal records under the proposals and a review carried out into whether the Attorney General should have the power to challenge "unduly lenient" sentences in such cases.
"Like most families in this country, I know first-hand that disability can affect anyone," Mr Byrne will say.
"Therefore it affects us all.
"Someone is registered disabled every three minutes. Yet, today disabled people are threatened by a vicious combination of hate crime, Atos and the Bedroom Tax.
"Today we deny disabled people peace of mind, a job, a home and care. We need to change this."
He will also say that he is working with Australian Labour MP Jenny Macklin on how a system her party introduced to integrate services could be used in the UK.
"We need a system that delivers the right help to the right people. So assessments have to stay.
"But let's take Andy Burnham's idea of whole person care and ask why not bring together health, social care and the back to work system into one comprehensive service.
"That's what Labour did in Australia. Let's see if we can do it here."
An Atos Healthcare spokesman said: "We have more than 13 years' experience in delivering welfare assessments and have worked closely with DWP under successive governments during that time.
"The WCA process in its entirety has been designed by government and all decisions about a claimant's benefit are taken by Decision Makers at DWP.
"We understand fully that the assessment process can cause huge anxiety and we do everything we can to treat people with sensitivity and compassion.
"Accusing a private provider of being responsible for the rise in successful appeals is a gross over simplification and ignores feedback from the Tribunal Service as well as a warning from the National Audit Office that there are dangers in that assumption.
"The number of decisions that are successfully appealed has risen in line with the number of assessments that are undertaken."
A spokeswoman for Work and Pensions Secretary Iain Duncan Smith said: "This Government is absolutely committed to supporting disabled people and we continue to spend around £50 billion a year on disabled people and their services.
"It was the previous government who introduced the WCA and we recognised it wasn't working as well as it should, which is why we have accepted all the recommendations from an independent expert we asked to carry out reviews.
"We also recently announced we will be bringing in additional providers to carry out the assessment, so the Labour Party are a bit behind the curve on this issue."