The Armed Forces Day Road Run, planned by volunteers, is due to take place on June 25.
A convoy of 60 military vehicles will gather and set off from Southwick, near Fareham, at 10am.
Vehicles, flanked by motorcycle outriders and lead by a safety car, and will go on a 37-mile journey across the county.
Volunteers have taken a year to plan the event.
One of the organisers is Graeme Cunningham, RN Engineer, a Falklands War veteran.
The organisers thanked parish and town councils and supporters for their help to bring the life.
A spokesman said they have been overwhelmed with the support shown by individuals and organisations, who were keen to express their thanks to the veterans.
The assembly time for the event is from 7.30am.
Approximately 700 people will be co-ordinating it.
Prominent guests include Wing Commander Mike Alabaster, attached to the nearby school of Policing, bishop Paul Miles-Knight and Woman’s Royal Army Corp Judith Kipling.
They will welcome Hampshire Royal British Legion members, veterans from across all three Armed Services, and their families.
A vintage coach will be hired for the veterans, with one guest being the mother of a soldier killed on active service in Iraq.
Thirty Royal British Legion riders will take part, and a contingent of seven riders from the South Atlantic Medals Association (SAMA).