The service included readings by veterans and political leaders, musical performances and re-enactments from D-Day.
World leaders including Donald Trump, the Queen, Angela Merkel and Theresa May were in the royal box to watch the event.
Here are some of the best pictures from the service.
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Prince Charles, Prince of Wales, Queen Elizabeth II, President of the United States, Donald Trump and First Lady of the United States, Melania Trump prepare to meet veterans. Picture: Jeff J Mitchell - WPA Pool /Getty Images | Getty Images Photo: D-Day 75
10. D-Day 75
US President Donald Trump talks with US First Lady Melania Trump in the royal box. Picture: CHRIS JACKSON/AFP/Getty Images | Getty Images Photo: -
11. D-Day 75
Members of the British Navy, Army and Royal Air Force (RAF) take part in an event to commemorate the 75th anniversary of the D-Day landings, in Portsmouth. Picture: MANDEL NGAN/AFP/Getty Images | Getty Images Photo: -
12. D-Day 75
Canadian Prime Minister Justin Trudeau (L) poses for a selfie photograph with Leader of Portsmouth City Council Gerald Vernon-Jackson during the event. Picture: CHRIS JACKSON/AFP/Getty Images | Getty Images Photo: -