The Dean informed the congregation at Derby Cathedral yesterday, and the Church of England made the announcement this morning.
He said: "I am a missioner at heart, passionate about growing the Church and helping people come to faith in Christ.
"My new role is all about enabling the Church of England to focus on these priorities, and as such it is one I had to say yes to.
"I will be sorry to leave Derby, but grateful for all we have accomplished here together. The Cathedral and Diocese will remain in my heart and my prayers."
Stephen will take up his new role at the end of September.