The Shanghai-listed unit of state-owned Cosco already has nearly 100 vessels itself, including ro-ro, MPP, general cargo and car carrier tonnage.
It said it was paying CNY 1.095bn ($176m) in cash for a 100% stake in Guangzhou Ocean.
Coscol added the deal would help it compete on an international level.
Guangzhou Ocean was established in 1961 and operates semi-submersible vessels, heavy-lifters, MPPs, bulkers and general cargoships, reefers, ro-ros and car carriers.
