Dwayne Johnson is to play former Hawaiian king Kamehameha in a new movie.

Dwayne Johnson

Dwayne Johnson

The 46-year-old actor has taken to his Instagram account to reveal he has been cast as the founder and first ruler of the Kingdom of Hawaii in forthcoming film 'The King', and admitted he is "humbled and grateful" to have signed up for his dream project.

He wrote: "KA LA HIKI OLA.

Dawning of a new day with hope and promise.

Humbled & grateful to begin this once in a lifetime journey.

KING KAMEHAMEHA - the legendary King was the first to unite the warring Hawaiian islands -- fulfilling the prophecy that surrounded his fabled life since birth and creating the powerful & spiritual 50th state as we know it today.

Academy Award winning director, Robert Zemeckis (FORREST GUMP) will direct.

Academy Award nominated writer, Randall Wallace (BRAVEHEART) will write. (sic)"

Johnson - who has Polynesian heritage, and spent part of his school days at President William McKinley High School in Honolulu, Hawaii - has wanted to play the king since he started his Hollywood acting career 17 years ago.

He added: "From the day I began my Hollywood career (2001), my dream was to bring this legacy to life.

In Polynesian culture we have a belief, that something isn't done when it's ready... it's done when it's right.

The time is right.

The one who walks alone. (sic)"

According to Deadline, Warner Bros. and New Line won an auction for 'The King', which will be produced by Johnson, Dany Garcia, Hiram Garcia, Beau Flynn, Zemeckis and Wallace.

The legendary king was the first person to unite the warring Hawaiian islands, which fulfilled a prophecy surrounding his life.

Wrestler-turned-actor Johnson has a tribal tattoo on his shoulder and chest in a nod to his Polynesian heritage, and his grandfather Peter Maivia was a pioneer of pro wrestling in Hawaii.

Filming is expected to start in 2020.