Ding Shumiao had taken two billion yuan (USD 322 million) in "agent fees" for helping former railways minister Liu Zhijun set up 57 rail projects involving 23 companies, Beijing's No 2 Intermediate People's Court said.
The 58-year-old also gave Liu 49 million yuan, added a statement posted on the court's verified account on Sina Weibo, a Chinese version of Twitter.
"The evidence was reliable and abundant," the court statement said in detailing the sentence of a 2.5 billion yuan (USD 400 million) fine and the lengthy prison term.
They also said that she had arranged sexual favours for the politician.
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Ding, who is also known as Ding Yuxin, reportedly started out in business as an egg vendor in the 1980s.
She was pictured in online reports at her sentencing todat wearing a pink sports pullover, flanked by security and looking visibly shaken and upset.
Liu was given a suspended death sentence last July after he was convicted of taking bribes worth 60 million yuan (USD 9.7 million) linked to rail construction projects.
But critics say no systemic reforms have been introduced to increase transparency to help battle endemic corruption.