Mirren portrayed Queen Elizabeth II in the hit 2006 film and they subsequently met in 2008 and again last year (11).
Now, the actress is in line for a third meeting after agreeing to help introduce acts during a show at England's Windsor Castle in honour of the royal's 60 years on the throne.
Susan Boyle, opera group Il Divo and entertainer Rolf Harris are among the performers who will take to the stage during the four-day event.
Simon Brooks Ward, the show's director and producer, says, "We have been overwhelmed by the goodwill and support from stars across the globe, who each have their own personal memories of the Queen, and share an enormous amount of love and respect for her work.
"The Diamond Jubilee Pageant will reflect the truly global impact the Queen has had during her 60-year reign, bringing horses, people, music and their culture from around the world to join the party."
The event will take place between 10 and 13 May (12), with Boyle performing on the final day, when the royals will attend.