The Sunday Mirror has been the sister newspaper of the Daily Mirror since 1963, but began life in 1915 as the Sunday Pictorial (known colloquially as "the Sunday Pic"). Published by Lord Rothermere, the paper's early goal was to strike a balance between general entertainment and quality journalism, with an emphasis on illustration and photography. And it found a great deal of early success in this regard, selling over one million copies per week just six months into its life.

This was largely due to its focus on topics which resonated with readers, such as politics, society and sport, which usually found themselves occupying the front pages. It was also in part due to one of the Pictorial's early contributors, Winston Churchill, whose articles would always garner attention and increase sales of a particular issue by as much as 400,000.

This kind of success began to wane, however, and around the 1930s circulation was dropping steadily. When 24-year-old journalist Hugh Cudlipp was appointed as editor in 1937, circulation once again began to rise, reaching well over one million before he went off to fight in the Second World War.

In 1988, a monthly magazine supplement (the Sunday Mirror Magazine) was attached to the main edition, which coincided with the paper being printed in full colour for the first time. The Sunday Mirror continues publishing online and in print with a circulation of around 500,000.