The 25-year-old actor initially auditioned for for part of a radiology student but subsequently signed to play charge nurse Adam Fearnley after show execs changed his character.
Speaking of his decision, Ryder said: "It's been a really difficult decision to make, but I feel it is the right one for me and the Royal Today."
A spokesperson for the programme confirmed to DS: "Jack Ryder has decided to step down from his role in The Royal Today. Jack felt too young for the part of Charge Nurse Adam Fearnley.
"He initially auditioned for a younger character, but during the drama's development it was decided he should play the more experienced Charge Nurse. After early rehearsals and filming, Jack discussed his concerns with Producer Ken Horn."
Producer Ken Horn added: "We appreciate Jack's decision and understand how he's reached it. We're grateful to him for all he's done for The Royal Today and wish him all the best for the future."
Programme makers are currently in the process of looking for a replacement to play the character.
Leah Bracknell takes a lead role in the show which begins filming this month.