Former MP Craig Thomson faces jail for using his Health Services Union (HSU) credit cards to pay for prostitutes and make cash withdrawals.
Thomson, 49, has been found guilty of dozens of dishonesty offences over the use of his credit cards to make cash withdrawals, pay for prostitutes and cigarettes and cover some of his former wife's travel expenses.
However, charges relating to Thomson hiring pornographic movies and other instances of using the card to pay for Christa Thomson's travel were dismissed.
Magistrate Charlie Rozencwajg said it was an "affront to common sense" that payments to escorts could ever be considered legitimate expenses.
He said Thomson must have known that using the cards for personal expenses was not allowed under the union's rules.
Thomson faces a maximum of five years in jail for the offences.
Thomson, who has strenuously denied any wrongdoing, showed no emotion as the verdict was read in the Melbourne Magistrates Court on Tuesday and made no comment to reporters.
Family members of HSU official Marco Bolano shouted "liar" as Thomson left the court.
Mr Bolano's partner Kylee Brehaut said the family had been through hell after Thomson used parliamentary privilege to accuse Mr Bolano of threatening to set him up with "hookers" to end his budding political career.
"You can't be happy about the misery of someone else, but that person has caused myself, my partner, my children, my family and Marco's family a lot of pain," Ms Brehaut told reporters.
Thomson was found guilty of six charges of obtaining financial advantage by deception over the payments to escorts, totalling more than $5500.
Mr Rozencwajg also found Thomson guilty of 16 charges of theft over the withdrawal of $6250 in cash.
Thomson was also found guilty of obtaining financial advantage by deception over the use of the cards to pay for cigarettes and for expenses incurred after he resigned from the union to become an MP.
Mr Rozencwajg said on some occasions Thomson was guilty of deception by using the cards to pay for Christa Thomson to travel, but not guilty over other occasions in which he paid for her flights and accommodation.
Buying movies while staying in hotels under union business did not meet the required standard to prove the charge of obtaining financial advantage by deception, he said.
Mr Rozencwajg said it did not matter that the movies were pornographic.
He ordered that Thomson not leave the country before his plea hearing on March 18, and to remain at a static address.
Thomson still faces proceedings at the Fair Work Commission over the alleged misuse of union funds.
HSU acting national secretary Chris Brown said Thomson had deceived and exploited union members.
"I promised the HSU members that we would seek to recover any monies stolen from the union and that is exactly what we intend to do," he said in a statement.
Federal Employment Minister Eric Abetz said Thomson misled parliament over the allegations and owes an apology to thousands of honest union members, as well as to parliament.
Thomson lost his NSW Central Coast seat of Dobell at last September's federal election, standing as an independent but receiving less than four per cent of the primary vote.