The employers testing workers include firms in the food, manufacturing, energy and retail sectors.
Public sector workers including those in job centres and transport networks are also set to be part of the testing programme with 27,000 tested.
Business lobbyists welcomed the use of rapid testing for staff who must attend work in person rather than logging in from home.
Matthew Fell at the Confederation of British Industry said: “Rapid mass testing is a key piece of the puzzle when it comes to getting on top of the virus. The health and safety of staff is paramount for employers, which is why they will be right behind this initiative.
“This expansion of testing will help more critical workers and those unable to work from home to operate safely, while also catching new cases more swiftly.”
The move comes as Royal Mail and BT’s Openreach network added their voices to firms lobbying the Government to prioritise their frontline workers in the queue for Covid vaccinations, the Mail on Sunday reported.
An Openreach spokesman said it wants its 25,000 field engineers who visit customers and maintain its network to be vaccinated after the most vulnerable have had jabs.
The CBI is already in talks with the Department of Health over the possibility of giving key workers in face-to-face industries priority for the vaccine.