The Health and Work Service, which will cover England, Wales and Scotland, will offer non-compulsory medical assessments and treatment plans.
It will be run by the private sector and paid for by scrapping compensation to employers for statutory sick pay.
Minister for Disabled People Mike Penning said sickness absence had a "substantial impact" on workers, employers and taxpayers.
"This is a triple-win. It will mean more people with a job, reduced cost for business, and a more financially secure future for Britain," he was quoted as saying by the BBC.
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Currently, staff who are off work for more than four weeks are considered to be long-term sick and entitled to Statutory Sick Pay of almost 90 pounds per week from their employers.
That will not change under the new arrangements - but the government wants the Health and Work Service to cut the number of people on long-term sick leave.
This is intended to identify the issues preventing an employee from returning to work and draw up a plan for them, their General Physicians and their employer, recommending how the employee can be helped back to work more quickly.
This may include fitness for work advice, medical care, working from home or retraining, the report said.
The scheme is not compulsory. Workers will be allowed to refuse to be assessed or to follow any course of action or treatment recommended, it said.
The service will be paid for by scrapping the Statutory Sick Pay Percentage Threshold Scheme (PTS), which gives some compensation to employers faced with high levels of sickness absence.
The Trades Union Congress said it supported anything that could help people get back to work when they are ill but underlined that care should be taken over how the scheme was implemented.
Officials say the new scheme may save companies up to 70 million pounds a year in reduced sickness pay and related costs. About one million people in Britain are off work long- term because of illness, according to the government.