Richard Lumby is to take over the firm's defence division, only three months after he was headhunted from Crown House, its M&E arm, to run infrastructure operations.
A Carillion spokesperson said the group set up the defence division after identifying it as as one of four growth markets. The others are health, transport and the Canadian PFI projects.
He said: "Defence is a growing market with contracts estimated at £25bn to come through. Very few have been allocated yet but we are waiting to hear back on a number of them."
These include the contract for the £200m Royal School of Military Engineering.
The spokesperson added that Lumby would be responsible for all the group's work in the defence sector and would pull together all the group's expertise in other divisions to mount bids for contracts.
"Defence work cuts across a lot of our existing businesses and involves using a lot of our other businesses such as building, services, consulting and training," he said. "Richard will tie together all the different businesses for each contract."
Future defence contracts are estimated at £25bn
Lumby's promotion is one of several changes in the roles of senior personnel.
Gordon Brydon, who was managing director of Carillion's services arm, has replaced Lumby as head of infrastructure. Brydon has been succeeded by Don Kenny, formerly of Johnson Controls, as managing director of services.
The spokesman said the changes were necessary to accommodate all the key staff.
Meanwhile, in another management change, Carillion has appointed Alan Hope managing director of its southern building business.
He takes over on 1 January from Mike Godfrey, who will retire from the group at the end of next year. He will stay on to pass the business over to Hope and do other work for the group.