Peter Skinner, 56, who was Labour MEP for the South East from 1999 to 2014, was found guilty of three charges after a trial at Southwark Crown Court.
Jurors heard he claimed thousands of pounds for support staff over a five-year period which actually funded hotel stays, restaurants and jewellery.
Skinner, of Snodland in Kent, will be sentenced on 29 April.
The politician also made fraudulent payments of £10,000 a month to his wife from December 2007 until July 2009, which entitled him to claim secretarial or parliamentary assistance allowance.
Skinner, who stood down as an MEP in 2014, also created a fake letter claiming his father was working for him, to justify his payments of £5,000 every three months, his trial heard.
He claimed he had been confused over the rules and blamed a lack of information given to him by the European Parliament.
Skinner was found guilty of one count of making a false instrument, one count of fraud and one count of false accounting between 2004 and 2009.
He was cleared of one count of making a false instrument in relation to a form submitted to the European Parliament in 2006.
An MEP who dishonestly claimed almost £500,000 in expenses has been warned he faces a prison sentence.