Mitchell will leave his role of Executive of Rugby for South African Super Rugby side the Bulls and join up with the rest of England coach Eddie Jones' staff this month to help prepare the national team for the upcoming November internationals.
The 54-year-old replaces Paul Gustard, who took over as head coach of Harlequins this season.
The RFU is understood to have paid the Bulls 400 thousand dollars in compensation, while Mitchell will be paid 600 thousand dollars for his year long stint with England.
