The property developer, a subsidiary of Liberty International, has acquired the remaining 50% share it needed to take full control of the group, which includes Earls Court, Olympia and the Brewery venues.
Capital & Counties bought an initial 50% stake in the venue group in 2007 and appointed architects to draw up a masterplan for the Earls Court site, with retail, leisure and residential uses under consideration.
The company, also known as Cap Co, last year submitted proposals to Hammersmith & Fulham Council for up to 10,000 homes on the 67-acre site, plus a hotel, office space, shopping and leisure facilities.
A Capital & Counties spokesman said: "We are working through options for the redevelopment of the site, with adjacent landowners Transport for London and Hammersmith & Fulham Council. It's important to point our that our thinking is still at an early stage and nothing has been finalised."