The private service, attended by about 450 family, friends, dignitaries and staff, was very different in style from recent royal funerals.
At the last - that of Princess Diana in 1997 - the service was relayed to thousands of people outside Westminster Abbey in London, and broadcast to millions around the world.
The Duke of Windsor, the former Edward VIII who abdicated in 1936 so he could marry his lover Wallis Simpson, was given a ceremonial funeral in 1972.
And exactly 50 years ago on Friday, Margaret's father King George VI had his state funeral, with large crowds lining the route to Windsor.
Gothic chapel
The service for Princess Margaret was held at St George's Chapel, in the grounds of Windsor Castle - which follows a royal tradition dating back more than 500 years.
The ornate gothic chapel is the final resting place of 10 former monarchs and several other royal figures.
The first sovereign to be buried there was King Edward IV in 1483, who ordered the building of the chapel as it is today in 1475.
Construction was continued under King Henry VI, who is also buried there, and completed in 1528 during the reign of King Henry VIII, another incumbent.
Other monarchs buried there are Charles 1 (executed in 1649), George III (died 1820), George IV (1830), William IV (1837), Edward VII (1910), and George V (1936).
Princess Margaret's father George VI was also interred in the chapel.
Modern chapel
But Margaret did break with tradition by choosing to be cremated - not unknown in royal history, but certainly unusual.
The venue was Slough Crematorium, only eight miles away from St George's Chapel but very different in style.
The plain crematorium, built in 1963, is a low-level brick building with a tiled roof and stained-glass windows.
Up to 15 services are day are conducted there, although on Friday Margaret's service was the sixth and last.
Margaret apparently ordered that there should be no ceremony at the crematorium, and no friends or family - just a few members of staff and palace officials.
Crematorium officials said a so-called committal service would be held, at which a final prayer is said as the coffin disappears.
The Princess's ashes, in a casket, were later being placed in the Royal Vault in St George's Chapel.
She is said to have decided against burial in the royal mausoleum at Frogmore in Windsor Great Park because she found it "very gloomy".
Royal family members buried there include Queen Victoria and Prince Albert, and the Duke and Duchess of Windsor.