Sun Zhengcai’s fall from grace saw seen him being named as a co-conspirator who sought to topple the president by the chairman of China’s securities regulator last October.
Sun was a former party leader of the western megacity of Chongqing, and a member of the Communist Party’s elite 25-member Politburo.
He was also seen as a candidate to be elevated to the Politburo Standing Committee, several officials who represent the apex of political power in China.
However, he is now the latest senior official be ensnared in a wide-ranging corruption clampdown launched by Mr Xi when he assumed power five years ago.
On the first day of his bribery trial on Thursday, Sun was accused of taking advantage of his position to seek profits for others and illegally accepting money, according to the Weibo account of the No.1 Intermediate People’s Court in the northern city of Tianjin.
Sun and his alleged associates were also charged with accepting money and goods worth 170 million yuan (£19 million) in return for providing help to unspecified organisations and individuals with engineering contracts, business operations and other matters.
Sun pleaded guilty and "expressed penitence", the court said, adding that it would make a ruling at a later date.
Mr Xi’s drive against graft has been criticised for lacking transparency and is seen by some as a means to sideline opponents.