The project, worth Rs 138 crore, was awarded by the public works department. It has timeframe of eight months.
"We are sure of executing this fast-track project in the given time to bring greater effulgence in the future," Unity Infraprojects vice-chairman and managing director Abhijit Avarsekar said in a statement.
With the addition of this project, the order book of the company now stands at Rs 4,232.17 crore.
On June 21, a major fire broke out on the fourth floor of Mantralay, killing five people, leaving several others injured, and destroying three floors.