The CIMIC Group was founded in 1949, and was formerly known as Leighton Holdings Limited. The company was first listed on the Australian Securities Exchange in 1962 and is based in Sydney, Australia.

CIMIC Group Limited, as the parent company of the CIMIC Group, owns and operates through a number of diverse Operating Companies: Leighton Contractors; Thiess; Pacific Partnerships; Leighton Services; EIC Activities; Leighton Asia, India and Offshore; and Leighton Properties. Amongst these Operating Companies are entities that have been in existence since the 1930s.

The CIMIC Group also has a 45% investment in the Habtoor Leighton Group and a 50% investment in a new Services entity.