In the past year, he has brought down potential rivals, notably the maverick politician Bo Xilai. He has used an anti-graft campaign to enforce his will on officials and is reported to have installed a special high-level police unit reporting directly to him. As chairman of the Central Military Commission, Xi has good links with the People's Liberation Army.
On top of all this, the plenum decided to create a national security committee to bring together the different branches of law enforcement at home and to co-ordinate policy abroad; there is no doubt that Xi or one of his lieutenants will head the new body. He also holds the state presidency and has been a frequent traveller to represent China at summits. Last week's plenum resolved to create a top body to oversee reform - it is a fair guess who will head it.
Xi has been preparing for this for a long time, showing every sign of being a masterly politician. He is what is known in China as a princeling - the child of a first-generation communist leader. These are the country's aristocracy. Somebody who knew him as a young man says he always carried with him a sense of entitlement.
But getting to the top was a long and winding road. His father, the revolutionary general Xi Zhongxun, was Deputy Prime Minister under Mao but then fell foul of the Cultural Revolution. His son was "sent down" to the countryside where he looked after pigs and was refused membership of the party.
The family's fortunes perked up when Deng won the power struggle set off by Mao's death in 1976, and Xi Zhongxun became governor of Guangdong province.
After finally gaining party membership, Xi graduated from a top Beijing university and then worked his way up through the administrative ranks before being elevated to China's top body, the Politburo Standing Committee in 2007.
On his way to the top, Xi, who will serve until 2022, gained a reputation as a conciliator. He has an easy public style; he smiles in public and was photographed recently with his trouser legs rolled up and holding his own umbrella as he inspected a river port.
But there is no doubting his complete attachment to the party state he heads.
This year has seen a toughening of the clampdown on dissent and an insistence by Xi on the need for absolute loyalty to the regime. He has resurrected Maoist ideology on party power.
Western ideas of plurality and democracy have no place in his people's republic. The potential clash between this assertion of political power and the need for economic and social reforms to maintain the momentum built up since Deng's reforms 30 years ago is the major question facing China - and the world for which it has such an importance.
* Jonathan Fenby, China Director of the research service Trusted Sources, is author of Tiger Head, Snake Tails; China Today and The Penguin History of Modern China.