Hundreds of members of the armed forces as well as cadets and veterans will take part in the Drumhead Service at Edinburgh Castle on August 10.
The service is the first in a five-year commemoration programme that will remember eight events from the war which had a significant impact on Scotland.
It will feature members of each of the services as well as music from three military bands, two cadet bands, three choirs and about 200 pipes and drums.
Almost 9000 people are expected to attend the service, which will be followed by a procession down the Royal Mile to Holyrood Park, where at least 1000 replica Commonwealth war gravestones will form a temporary memorial.
Brigadier David Allfrey, producer of the Royal Edinburgh Military Tattoo and chief organiser of the event, said: "It promises to be a very memorable occasion."
Culture Secretary Fiona Hyslop said: "A hundred years ago nobody could have foreseen the tragedy that was to affect every town, village, community and family in Scotland - claiming the lives of more than 100,000 Scots, leaving many more injured or disabled and forcing their loved ones to come to terms with the terrible consequences.
"It is right that we remember that brutal conflict and reflect on how it shaped our society.
"That is why, from the centenary of the outbreak of the First World War until January 2019, we will encourage the people of Scotland and those with connections to Scotland to recognise the significant and broad impact the First World War had on our nation, and to reflect on its lasting social and civic legacy."
A thousand free places for the event were snapped up within two days. A further 600 seats have since been released and around 200 are still available on www.WW100Scotland.com.
l See Monday's Herald for a 28-page First World War supplement.