The former Leicester captain cannot start his job until July because his wife is expecting their second child and this has forced Andrew to take the acting manager's position.
With Ashton out of the way, England were without a leader for the tour to New Zealand - highlighting the trouble the RFU got themselves into over Ashton.
Johnson, who has never held a coaching or managerial role in rugby, said: "This is a great honour. I'm passionate about the England team and delivering success for it. While I cannot take up my position until 1 July I'll be working with Rob and the England management to select the team to face the Barbarians for the New Zealand tour as well as selecting the elite player squad 32 under the new agreement with the clubs."
With Johnson installed, the focus now falls on Andrew and his handling of what many consider to be a public relations disaster.
Andrew did not keep Ashton informed about developments and left the head coach out to dry.
He told Ashton about his fate yesterday afternoon and appeared to dress up the job offer today by describing it as a 'senior position'.
Andrew said: "I'd like to thank Brian for a very good job that he did in difficult circumstances."
