South China Morning Post said the amount of bribes involved was punishable by death but the court said it took mitigating factors into account, including that most of the bribes were taken by "designated parties" and that Sun gave investigators additional, previously unknown information about his crimes.
Sun served as the CPC's chief in Shunyi District, Beijing; Standing Committee member and secretary general of the CPC's Beijing Municipal Committee; agriculture minister; secretary of the CPC's Jilin Provincial Committee; Political Bureau member of the CPC Central Committee; and Party chief of Chongqing Municipality, according to the Tianjin Court.
Sun Zhengcai, a former politburo member and party boss of the southwestern city of Chongqing, is one of the highest officials to be toppled by an anti-graft campaign that critics say is Xi's way to root out rivals rather than corruption.
"I sincerely confess to and regret the crimes I committed".
Sun was a member of the Communist Party's key decision-making body, the Politburo, but was expelled from the party in September, before being handed over to prosecutors.
During the conference, Sun, and a former party boss in Chongqing, Bo Xilai, were accused of being part of a plot to usurp the power of the Communist Party.
Notably, while Sun was sentenced to life in prison for corruption, the Party appears to have found him guilty of a more serious offense - challenging Xi's unquestionable authority.
His clampdown on corrupt officials has gained him a measure of popularity among Chinese people.
Xi's rise over the years has been accompanied by tighter restrictions on civil society, with the detention of activists and lawyers, and stricter limits on the already heavily controlled internet.
The Chinese president said in April, though, that he is opposed to life-long rule, arguing that the move to amend the constitution was definitely misinterpreted by foreign observers.