The 15-minute film, To Unwill a Heart, used local actors and was shot around the city’s medieval landmarks.
It was developed by film staff and historians at Southampton Solent University.
The film was also shown at the Cannes Short Film Corner, part of the international film festival.
Writer and director Gela Jenssen researched the legend of Sir Bevois, who was the son of Sir Guy, Earl of Hampton.
Ms Jenssen used historical documents recounting storytellers’ accounts of Sir Bevois’ adventures.
They include being sold to slave merchants by his mother, ending up in the court of the king of Armenia and falling in love with a princess.
He reputedly returned to England to reclaim his father’s land, and founded the city of Southampton.
Cast and crew will be among 300 guests attending the premiere at the Harbour Lights Picturehouse later.
Ms Jenssen said: “It’s exciting to show the film to the people of Southampton, get their reaction – many of them don’t recognise the legend.
“After hundreds of years, the story deserves to be told.”
The production team is also submitting ideas for a feature length version to several film companies.
Although the authenticity of the legend is debated, the two stone lions at the city’s Bargate represent two lions the knight is reputed to have slain.
Source: BBC News