The hit BBC One show will bow out with a two-part special, airing this Christmas.
Co-creators and executive producers Johnny Capps and Julian Murphy confirmed in a statement that the fifth series of the show would be its last, saying: "This is the series where the storylines truly reach their apex.
"We always felt the story of the legend was best told across five series, leading to a spectacular finale that draws on the best known elements of this much-loved story and brings to a conclusion the battle for Camelot.
"We'd like to thank the amazing cast and crew for their professionalism and dedication, the BBC, FME and all of our partners globally for their incredible support and encouragement across the last five series. But chiefly, our thanks go to Merlin's remarkable and loyal audience around the world for their enthusiasm for the characters and Camelot universe."
BBC One controller Danny Cohen said: "Merlin's mix of magic, adventure and humour quickly became a hit with BBC One audiences and has continued to thrill families over the last five years on Saturday nights. I admire the creators' decision to end Merlin on a high, but also know that we will miss it in the BBC One schedule.
"On behalf of BBC One I would like to thank Shine and all those involved in the making of the show both on and off screen. I hope fans will tune in over the coming weeks to see the spectacularly dramatic final episodes, and we have ambitious plans for new drama in the Saturday evening slot in 2013."
Merlin's final series is currently airing on BBC One on Saturday.
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