The Government will unveil the latest phase of its "radical" welfare reforms by announcing contracts worth up to £5 billion to deliver its new Work Programme.
Ministers said private firms, voluntary groups and the public sector will be used to deliver the biggest ever payments by results programme, adding that it could be used as a blueprint for other public services.
Contracts will be worth between £3 billion and £5 billion over seven years, with organisations being paid using benefit savings made from getting people into work.
Employment minister Chris Grayling warned jobseekers they will lose their benefit if they do not take up support being offered to help them find work.
He said: "There are almost five million people across the country who were left untouched on out of work benefits - we have to provide them with the right help and support to get back to work.
"Today we will be setting out a completely new way of helping people off benefits and getting them back into work."
Organisations will be paid on a sliding scale, up to £14,000 for getting someone on incapacity benefit into work and keeping them there for two years.
The Government said it expects more than a million people to be covered by the Work Programme over the first two years.
When the contracts were put out to tender, the Government received more than 170 bids from 30 different organisations.
Liam Byrne, Labour's shadow work and pensions secretary, said: "After a Budget that put 200,000 more on the dole, this Work Programme has its work cut out. Most people will be really worried that this thinned down programme is simply not enough to get Britain back to work."