Princess Margaret married the photographer Antony Armstrong‑Jones, who later became known as Antony Armstrong‑Jones, 1st Earl of Snowdon.

She met Antony at a dinner/supper party in 1958, and the couple became secretly engaged in late 1959 before the engagement was publicly announced in February 1960. They married at Westminster Abbey in London on 6 May 1960, in a ceremony that made history as the first royal wedding to be broadcast on television and was watched by an estimated 300 million people worldwide. After the wedding he was created Earl of Snowdon, which is why he is often referred to as Lord Snowdon in later accounts.

Their marriage lasted until 1978 and they had two children together, David and Sarah.