The verdict could send him to prison and looks to have crushed his hopes for a political comeback.
The development ends the most serious legal battle 68-year-old Olmert has faced since he was forced to step down as prime minister in 2009 amid a flurry of corruption allegations.
It also caps off a political career that saw Olmert transform himself from a sharp-tongued backbencher in the hardline Likud Party into a global statesman whose push for peace with the Palestinians came crashing down due to his legal troubles.
The Tel Aviv district court handed down its verdict in a Jerusalem property scandal case related to Olmert's activities before he became prime minister in 2006.
A total of 13 government officials, developers and other business people were charged in connection with three separate schemes related to the Holyland housing development in Jerusalem, in what was regarded as perhaps the largest corruption scandal ever exposed in Israel.
"It is not an easy day for Olmert," his lawyer Roy Blecher said as he left the court.
Legal experts said Olmert almost certainly faces a jail term when he is sentenced on April 28.
According to the original 2012 indictment, millions of dollars illegally changed hands to promote a series of property projects, including a controversial housing development in Jerusalem that required a radical change in zoning laws and earned the developers tax breaks and other benefits.
Olmert was charged over acts committed while he was mayor of Jerusalem and minister of industry and trade. He was accused of taking bribes to push the project forward.
The conviction puts a dramatic end to Olmert's long political career, which was dogged by corruption allegations which, until now, rarely stuck.