The 37-year-old actor, who put on 20 pounds and worked hard on his physique for the role, said he did not think if he was even in the middle of Ritchie's list.
"Guy flat-out said he didn't want to see me. I thought, wait, he's not even going to give me audition? ...We knew a lot of the same people, and before this film even came up, I kept hearing from friends that Guy and I should work together. So I had this construct in my mind that Guy and I were already pals. I wanted him to at least have a cup of tea with me," Hunnam said in a statement.
"Finally, Guy invited me to read for him, and then read again with some other actors. A week later I got the call and Guy said, 'Alright, you got the role.' I was both surprised and overjoyed," Hunnam said.
The actor said the story of King Arthur is about self belief and the idea of conquering over inner fears interested him the most.
"The thing that really interested me and Guy, and which is inherent in the Arthurian legend, is the idea that the challenges we face are only given weight by our fears," Hunnam said.