It is hoped the support will help the NHS get through what Nicola Sturgeon warned will be the “hardest winter in any of our memories”.
Health secretary Humza Yousaf announced a raft of other measures on Tuesday, including a £20 million investment and support from the fire service and Red Cross, as well as some non-emergency patients being taken to hospital by taxi.
Some 114 military personnel will be deployed from Saturday, primarily as non-emergency drivers. Each will be paired with a clinician.
Support will focus on the Central Belt, including Glasgow, Lanarkshire, Ayrshire and Arran, Fife and Edinburgh.
Another 111 personnel will deploy to operate mobile testing units from Wednesday, September 29.
It comes after the Scottish Government submitted a request for military aid last week amid growing pressure on the NHS and ambulance service.
Around 100 second year paramedic students will also be asked to help in ambulance control rooms, Mr Yousaf said.
Work will also be done to reduce admission waiting times at A&E departments, which cause delays to ambulances.
But the union Unite warned these measures “will not be enough”, adding more should have been done earlier.
"The announcement by the health secretary is welcome and there is progress on a number of fronts including extra investment, extra call handers, and support from the Army, and fire and rescue services, which Unite urgently requested," said Jamie McNamee, Unite convenor at the Scottish Ambulance Service.
"However, the reality is that it has been a delayed response and far more should have been done earlier.”
Ms Sturgeon admitted the NHS was facing “crisis conditions” in an earlier update on Tuesday afternoon.
"I believe this will be the hardest winter that the NHS has faced in any of our memories,” she said.
Mr Yousaf later told MSPs on Tuesday the Scottish Ambulance service was experiencing “unprecedented demand”, alongside ambulance services in the rest of the UK and the wider NHS, “largely because of Covid-19, but also due to a combination of increasingly complex cases, and exceptionally busy emergency departments”.
“The Scottish Ambulance Service is the heartbeat of our NHS,” he said.
"It has a unique role in engaging with all parts of the health and social care system across the whole of Scotland – 24 hours of every day. It is vital that we ensure it has the support it needs to perform this crucial role."
He added: “The measures we have announced today will begin to address some of these issues, both improving the level of service for the public, and also helping to reduce the pressure on the workforce, who are doing so much to serve the public during these incredibly demanding times.”
It comes after performance on waiting times at A&E departments in Scotland reached record lows for the fifth time in six weeks.
Just 71.5 per cent of people visiting A&E in the week to September 12 were seen within four hours, a drop from the figure of 74.6 per cent the week before. The Scottish Government target is 95 per cent.
And figures obtained by The Scotsman show the number of less-urgent ambulance calls which waited more than 12 hours for a response increased 20 times in the past year.
Some 297 patient calls in the least urgent or “yellow” category waited at least 12 hours for an ambulance between August 2020 and July this year, compared to 15 the previous year.
Opposition MSPs accused the health secretary of not doing enough to combat the problems faced by the NHS and ambulance service.
"This situation is unacceptable,” said Liberal Democrat leader Alex Cole-Hamilton.
"It is not just the pandemic, and to suggest it is undermines the very real concerns that staff have been expressing for a long time before we heard of Covid-19.
"It should never reached the stage where the fire service, the Army and taxi drivers have to bail out frontline care staff."
Scottish Conservative health spokesperson Sandesh Gulhane said: “Humza Yousaf’s flimsy NHS plan is not cutting it. Since it was published, things have got worse.
“My colleagues are doing all they can. Nurses, doctors and paramedics are all working flat out.
“Scotland’s NHS needs a real plan to tackle one of the worst winters it will ever face.”
Labour’s Jackie Baillie called on Mr Yousaf to “urgently consider temporary wards or field hospitals like the Louisa Jordan”.
Ms Baillie highlighted comments from John Thomson, vice-president for the Royal College of Emergency Medicine in Scotland.
Dr Thomson told the BBC he estimates a shortage of around 1,000 beds in A&E departments across Scotland, which causes delays to new admissions.
The Scottish Ambulance Service has previously said it would welcome the setting up of temporary admission wards, which are among the measures planned by Mr Yousaf and would supersede any requirement for field hospitals.
A Scottish Ambulance Service spokesperson said on Tuesday: “Targeted military assistance has been requested to provide additional capacity to assist with service pressures.
"We are anticipating over 100 military staff, including trained drivers coming in and this will help free up our paramedics and technicians to focus solely on providing patients with the best clinical care. If approved, these military personnel will be deployed to the areas of Scotland where there is most pressure on our crews and services.”
Brigadier Ben Wrench, Commander of Joint Military Command Scotland, said the MoD was working closely with the Scottish Government and Scottish Ambulance Service.
“Our servicemen and women, drawn from units in Scotland and elsewhere, are always proud to support the NHS and the other emergency services,” he said.
"Opportunities like this allow the Armed Forces to demonstrate their adaptability and teamwork in providing assistance to local communities.”