Princess Anne took the salute in Salisbury before meeting personnel at the event's military village (Pictures: MOD).
The annual event is a chance for the whole country to celebrate the work of service personnel, reservists, veterans, cadets and their families and friends.
Salisbury is hosting the occasion's national event, following Liverpool and Llandudno in recent years, with other celebrations being held around the world.
On what was forecast to be the hottest day of the year in the UK, Princess Anne took the salute during a parade of more than 1,300 service personnel, cadets and veterans through Salisbury.
You can watch back the parade in full here.
In a recorded message to mark Armed Forces Day, Prime Minister Theresa May said she is "proud" to celebrate the event and paid tribute to the "wonderful men and women who serve".
Defence Secretary Penny Mordaunt also attended the celebrations and met serving personnel in the military village in Salisbury's Hudson's Field.
Ms Mordaunt praised the city's response following a nerve agent attack last year.