Fitz-Henley will star opposite Murray Fraser as the Prince in the Lifetime network's "Harry & Meghan: The Royal Love Story."
British-born Fraser has previously appeared in U.K. TV series "The Loch" and "Victoria."
The film will begin with the couple's first date in May, 2016, which was set up by a mutual friend, and it will include a number of romantic outings up until its big engagement announcement last November.
The project, directed by "The Royals'" Menhaj Huda, will air this spring.
Prince Harry and Meghan are set to tie the knot at Windsor Castle, England, on May 19.
It's not the first real-life royal romance to get the small screen treatment at Lifetime - Harry's brother Prince William and his wife, Catherine, Duchess of Cambridge, were also the subjects of a 2011 film, called "William & Kate: The Movie," starring Camilla Luddington and Nico Evers-Swindell as the happy couple.