The series will premiere with the first half of a two-parter titled 'Arthur's Bane'.
Series five will see the return of regular cast members Colin Morgan (Merlin), Angel Coulby (Gwen), Bradley James (Arthur), Katie McGrath (Morgana) and Richard Wilson (Gaius).
Co-creator and executive producer Johnny Capps also revealed at Comic-Con that Anthony Head will reprise his role as Uther Pendragon as a guest star.
Game of Thrones star Liam Cunningham was confirmed to join the cast back in April, while John Bradley will play a character named Tyr Seward.
Watch the cast of Merlin discuss the fantasy drama's fifth run with Digital Spy below: