Ringrose’s appointment will take effect on 1 July next year after six months as deputy chief executive.
The decision to promote Ringrose follows the announcement in May that the roles of chairman and chief executive were to be split.
Mike Bottjer has been chairman for nearly seven years and chief executive for almost almost nine.
He will remain as chairman but is expected to cut back the time he spends at the company from next December.
Ringrose has been with Interserve for five years and is an executive director with special responsibility for the facility services division.
In another shake-up, Clive Groom will retire as executive director on
31 December next year and two other non-executive directors will also step down.