The movie starts out with a girl, a to be bride, Sophie, posting three wedding invitations to three different men that might be her father, without telling her mother. She then shares the secret with her two best friends, Ali and Lisa.
Her mother reunites with her former Donna and The Dynamos band-mates. The three men arrive, and Sophie, smuggled them to the goat house. But Donna, discovers that secret.
At Sophie's bachelorette party, Donna and The Dynamos perform a performance. She learns quite a bit from the three men. But Sophie cannot handle the truth, and faints on the dance floor.
With her big plans falling apart and wedding in jeopardy, she tells her boyfriend, Sky, all about it. He reacts angrily to it, and Sophie turns to her mother for support.
When the wedding ceremony starts, Donna, her mother confesses that her father is present at the wedding. The three men concur that they would be quite happy to be one-third of a father of Sophie. She then tells Sky that they should postpone the wedding and travel around the world first. Sam, one of the men, proposes to Donna and she accepts, and they go through an impromptu ceremony.
The story conclude as Sophie and Sky bid farewell to Skopelos island and sail away to a new life, together.