Cheung Kong Infrastructure (Holdings) (CKI) and its utility arm - Hongkong Electric Holdings - will pay A$2.31 billion (about HK$10.49 billion) for Powercor Australia, an electricity distributor and retailer in Victoria state.
CKI chairman Victor Li Tzar-kuoi said the investment was part of a globalisation plan in which the companies would seek investments in North America, Asia and the mainland.
Powercor, the largest of five electricity distributors in Victoria, is the second power investment in Australia by CKI and its 38.9 per cent-owned Hong Kong Electric.
In December, the companies purchased ETSA Utilities, a power distributor in South Australia, for A$3.25 billion.
The latest purchase by a recently formed 50:50 joint venture brought the investment by the companies in Australia to HK$27 billion, Mr Li said.
CKI managing director Kam Hing-lam said Powercor would be a low-risk investment with a steady return for the companies.