The 55,000-ton carrier, formerly known as the Soviet ship Varyag, was renamed Liaoning during the commissioning ceremony that was overseen by Hu and Premier Wen Jiabao, China's state-owned newspaper China Daily reported.
With the commissioning, China joined the small group of nations -- the United States, the United Kingdom, France, Russia, Spain, Italy, India, Brazil and Thailand -- operating aircraft carriers.
China bought the hull of the unfinished vessel in 1998, with no guns and engines, from a Ukrainian shipyard where it had been under construction. It was unfinished when the Soviet Union collapsed in 1991, leaving Ukraine with Soviet bases and equipment.
The vessel, an Admiral Kuznetsov class carrier, measures around 1,000 feet in length and 122 feet wide at the water line.
The Liaoning was handed over by the navy's main contractor, the China Shipbuilding Industry Corp.
China announced in March that it was nearing commissioning of the vessel, which will be deployed in the increasingly political arena of the South China Sea, the Shanghai Daily newspaper reported at the time.
But during the ceremony at a naval base in northeastern city of Dalian, at the southern tip of Liaoning province, the Central Military Commission reiterated that the ship "will continue to serve scientific research purposes, as well as military training," the China Daily report said.
"It will also be of great significance in enhancing national defense power and the country's comprehensive strength," Wen said.
"China's development of an aircraft carrier was an important strategic decision made by the Communist Party of China Central Committee, the State Council and the Central Military Commission."
The vessel, which has undergone months of sea trials, will likely have domestically built J-15 fighters -- still under development -- flying from its upward-curved flight deck, a report by the website Naval-Technology said earlier this year.
The J-15, called The Shark, is believed to be a modified version of a Russian Su-33 prototype, also purchased from the Ukraine, Global Security website reports. The J-15 is designed to fly from so-called ski-jump carriers, like Varyag, rather than carriers designed to launch aircraft using a catapult.
The Liaoning commissioning comes as China's State Oceanic Administration said it aims to use unmanned aerial vehicles to strengthen marine surveillance by 2015.
The SOA recently set up a pilot program of using drones to undertake remote-sensing marine surveillance in Lianyungang, a coastal city in eastern Jiangsu province, a report by the state-run Xinhua news agency said.
The SOA also wants the drones to be used for surveillance of South China Sea islands and islets whose ownership Beijing is disputing.
The territories include the Diaoyu Islands -- known as the Senkakus by Japan -- and Huangyan Island, called the Scarborough Shoal by the Philippines which controls them.
China also launched the lead ship of its second-generation Aegis destroyer class in a shipyard in Shanghai at the end of August, Global Times reported earlier this month.