She will play Juliet in the famous balcony scene from William Shakespeare's Romeo and Juliet in a London charity show.
Her performance Monday, at the Globe Theatre in London, will be in front of Charles and his escort Camilla Parker Bowles.
It will be one of the first times Camilla has gone to an official engagement with the prince.
Joseph Fiennes, Gwyneth's co-star in the film "Shakespeare in Love," will play Romeo.
The balcony scene was a central part of the film, which won Gwyneth an Oscar.
Charles and Camilla will meet Gwyneth, 30, and other performers at an after-show party.
The show is expected to raise thousands for the Prince's Trust with tickets costing up to $475.