Mr Justice Newey made criticisms as he ruled on a dispute between Mr Ecclestone, 83, and Constantin Medien at a High Court hearing in London.
Mr Ecclestone had been accused of entering into a "corrupt agreement" with a banker to facilitate the sale of the Formula 1 Group to a buyer chosen by him.
Constantin Medien said it lost out as a result of the deal and wanted tens of millions of pounds in compensation.
Mr Ecclestone, chief executive of the Formula 1 Group, said Constantin Medien's claim "lacks any merit" and denied any conspiracy.
The judge dismissed the claim yesterday but he concluded that payments made were a "bribe".
He said they were made because Mr Ecclestone had entered into a "corrupt agreement" with the banker in 2005.
But he said no loss to Constantin had been shown to have been caused and therefore the company's claim failed.
The judge heard that Constantin wanted around £80 million damages.
"Even... making allowances for the lapse of time and Mr Ecclestone's age, I am afraid that I find it impossible to regard him as a reliable or truthful witness," said Mr Justice Newey, in a written ruling.
"The payments were a bribe. They were made because Mr Ecclestone had entered into a corrupt agreement with Dr Gribkowsky in May 2005."
After the ruling, Mr Ecclestone said: "Whether I told the truth or not... questions were asked, I answered them and I told the truth. This was an opinion that had nothing to do with the case."