The still-unnamed carrier was launched this time last year but since then has been undergoing fitting of weapons and other systems and has not yet entered service.
Chinese President Xi Jinping is overseeing an ambitious military modernisation scheme, including stealth jets and anti-satellite missiles, as China ramps up its presence in the disputed South China Sea and around self-ruled Taiwan, an island it considers its own.
Online Chinese news portals, including Sina, showed pictures on their sites on Monday of the ship being eased out of its dock by tugs, though it was unclear where it might be heading. Monday is the 69th anniversary of the founding of modern China's navy.
The report said the carrier was likely being readied for its first sea trials.
China's Defence Ministry did not respond to a request for comment.
Pictures of the carrier have been widely leaked on the Chinese internet, with little apparent concern from the government.
State media has previously quoted military experts as saying the carrier, China's second, is not expected to enter service until 2020, once it has been fully kitted out and armed.
Little is known about China's aircraft carrier programme, which is a state secret.
The new conventionally powered carrier will be able to operate China's Shenyang J-15 fighter jets.
Unlike the U.S. navy's longer-range nuclear carriers, both of China's feature Soviet-design ski-jump bows, intended to give fighter jets enough lift to take off from their shorter decks. But they lack the powerful catapult technology for launching aircraft of their U.S. counterparts.
The Liaoning has taken part in military exercises, including in the South China Sea and Western Pacific, but is expected to serve more as a training vessel.
Taiwan has said China is actually building two new aircraft carriers, but China has not officially confirmed the existence of another carrier.
Chinese state media has quoted experts as saying that the country needs at least six carriers. The United States operates 10 and plans to build two more.
Most experts agree that developing such a force will be a decades-long endeavour for China but the launch of the second carrier holds a certain prestige value for Beijing, seen by many analysts as keen to eventually erode U.S. military prominence in the region.
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.