The three 90-minute crime dramas are to be filmed this summer on location in Ystad in southern Sweden, home of fictional detective Kurt Wallander. Mankell's series of books on the life of the enigmatic police inspector have achieved great international success, selling 10 million copies worldwide.
According to Mankell's production company Yellow Bird, the Academy Award-nominated actor got in touch with them last year requesting to play the title role.
Branagh told Broadcast: "Wallander is a wonderfully complex and compelling character and I am excited to be playing this fascinatingly flawed but deeply human detective,"
The films are to be based on the first three novels in the Wallander series: Sidetracked, Firewall and One Step Behind.
"This is more than just a detective series. It's fantastic drama, great stories and an absolutely beautiful setting," Andy Harries, head of newly founded production company Left Bank Pictures, told Broadcast.
"Visually these films are going to be very strong, very picture postcard. Ken Branagh is perfect for the title role," he added.
Left Bank Pictures has been commissioned by the BBC to make the Wallander series in association with Yellow Bird.
"Branagh thinks the books are fantastic," Yellow Bird CEO Mikael Wallén told Dagens Nyheter.
"For this reason I believe it will be a success. His company will also be a co-producer," he added.
Kenneth Branagh recently directed the film Sleuth, starring Michael Caine and Jude Law. He is however best known for his screen adaptations of the plays of William Shakespeare, including Henry V, Much Ado About Nothing, Hamlet and As You Like It.
According to Broadcast, the BBC is searching for a drama vehicle to rival the successes of ITV's Inspector Morse, Cracker and Prime Suspect.
The three films are expected to cost a combined total of £6 million (77 million kronor, $12 million) to produce.