Miller is currently working on a residential and retail scheme for Midland & City Developments at Fleet Street, and a new entrance and shops for Heartlands Hospital.
Public spending on education, health, housing and prisons is driving demand in the Midlands, despite a slowdown in the commercial sector since 11 September.
Harrison said: "The launch of a Birmingham office reinforces our commitment to the area and reflects our view of the West Midlands as an extremely important marketplace."
Miller Construction currently has offices in Wakefield, Manchester, Newcastle, Nottingham and Windsor as well as its Edinburgh headquarters.
Miller's expansion into the Midlands follows Costain's move into the area earlier this year.
Costain recruited regional director Mike Thompson from Interserve in February to head its new Birmingham office.