The MOD says it has "contacted employers" to advise them of the next step in their "intelligent mobilisation" of Reserve Forces during the outbreak.
The department said only reservists with "specialist skills that meet specific requests for help" from the Government will be required.
In an update posted on the Government website, the MOD said the reservists would be deployed for tasks including "providing additional medical and logistical support for the NHS".
Other activities could include "acting as liaison officers and deploying specialist skills such as engineering and accounting."
The 3,000 personnel are set to be mobilised for six months - a time period that will be "kept under review".
James Heappey, Minister for the Armed Forces, said: "To be able to draw on that pool of talent and expertise is invaluable."
He added: "Our reservists are a truly remarkable group of people; each with their own skills and experience from their civilian careers beyond the armed forces.
"I know that our reservists will answer the nation’s call with real enthusiasm and will play a key part in our response to Covid-19."
In a letter to employers advising them of the move, Major General Simon Brooks-Ward wrote: "We are confident, at this time of national emergency, that employers will do everything they can to support us in combatting this dreadful virus."