This year's national event in Scarborough was postponed until 2022 because of the coronavirus pandemic – called off for the second consecutive year.
Instead, a special lunch was held for 100 service personnel and their families at the National Memorial Arboretum in Staffordshire.
Many of those invited have supported the UK's response to COVID-19, from driving ambulances to supporting the vaccination programme.
In London, the 13 bridge walking challenge took place in aid of SSAFA, the Armed Forces charity.
A special tribute to the Armed Forces also took over the iconic billboards of London's Piccadilly Circus, as the monumental screens showed portraits of personnel beside a national "thank you" message.
On Thursday 24 June, Boris Johnson visited 4th Battalion The Rifles at New Normandy Barracks in Aldershot to meet and thank personnel.
The Prime Minister later hosted a reception in the Rose Garden at 10 Downing Street for military personnel, to thank them for their work defending sea, land and sky and supporting the UK in a time of crisis.
"I'm immensely proud that the UK is defended by, without doubt, the finest armed services you'll find anywhere in the world," said the Prime Minister.
"Our fantastic men and women in uniform are the best trained, the best led, the most dedicated bunch of people you will ever meet.
"This year we have witnessed the full breadth of what the Armed Forces can do – from being on the frontline in our fight against COVID to work fighting terrorism, delivering aid and flying the flag for the UK internationally.
"This Armed Forces Day, on behalf of the nation, I want to say a huge thank you for everything you do. We owe you more than I can ever say."
Labour leader Sir Keir Starmer tweeted: "Every day, men and women in our Armed Forces put their lives on the line to save others.
"You are the best of our country. The Labour Party will always stand with you."
Defence Secretary Ben Wallace said: "Our personnel are defence's greatest asset and their work over the last year, both at home and overseas, is testament to that.
"This Armed Forces Day, I hope the whole nation will come together to thank the entire Armed Forces community for everything they do and the sacrifices they make to defend our way of life."
Cover image: Prime Minister Boris Johnson hosting an Armed Forces Day reception for serving members of the UK Armed Forces in the garden of 10 Downing Street to coincide with Armed Forces Week (Picture: No 10 Downing Street).