Addressing about 70 leaders in Paris – including US President Donald Trump and Russian President Vladimir Putin – he called on them to “fight for peace”.
“Let us build our hopes rather than playing our fears against each other,” he said.
Many other events have been taking place around the world.
Some 9.7 million soldiers and 10 million civilians died in World War One, which lasted from 1914 to 1918.
What happened in Paris?
Mr Macron and dignitaries marched to the Tomb of the Unknown Soldier, a memorial to France’s fallen under the Arc de Triomphe, in the rain under black umbrellas as church bells tolled through the city.
In a speech lasting nearly 20 minutes, the French leader urged his fellow leaders not to forget the lessons of the past.
“Ruining this hope with a fascination for withdrawal, violence or domination would be a mistake for which future generations would rightly find us responsible,” he added.
He described nationalism as a “betrayal of patriotism”.
The service ended with the bugle call that was played at 11:00 on 11 November 1918 to signal the end of hostilities on the Western Front.
Just before the leaders assembled, a topless female protester with the words “fake peacemaker” written on her chest came within a few metres of Mr Trump’s motorcade before being apprehended.
Sunday afternoon will see Mr Macron and German Chancellor Angela Merkel attend a peace conference – the Paris Peace Forum – with leaders including Russian President Vladimir Putin and Turkey’s Recep Tayyip Erdogan.
On Saturday, Mr Macron and Mrs Merkel visited the town of Compiègne in northern France. They signed a book of remembrance in a railway carriage identical to the one in which the 1918 Armistice was sealed.
President Trump, however, caused controversy by cancelling a trip to a cemetery for the war dead because of bad weather.
A group of around 50 activist organisations plan to hold a demonstration in Paris later on Sunday in protest against the US leader’s visit.
Which events have already taken place?
In Australia, a ceremony was held at the National War Memorial in Canberra, while in Adelaide an aircraft dropped thousands of red paper poppies.
During his speech in Canberra, Australian Prime Minister Scott Morrison spoke of the importance of remembrance, saying people need “to learn from the past so that we can better navigate the changing currents of our own times, for our own children, and for the next generations”.
In New Zealand, a gun salute took place in the capital, Wellington.
And in India, memorials were held for the 74,000 troops who died fighting on the other side of the world.
“This was a war in which India was not directly involved, yet our soldiers fought world-over, just for the cause of peace,” Prime Minister Narendra Modi tweeted on Sunday.
Meanwhile in the UK, a series of special events is being held to mark the end of the 1914-18 conflict.