Ex-Labour MP Jim Devine has been found guilty of dishonestly claiming £8,385 of expenses by using false invoices for cleaning and printing work.
The ex-MP for Livingston, 57, was found guilty on two counts, but cleared of a third count, relating to £360.
Devine nodded as the verdicts were delivered. Sentencing is in four weeks. The maximum jail term is seven years.
He was the first MP to stand trial in the wake of the revelations about Parliamentary expenses claims.
The jury took two hours and 45 minutes to agree their verdicts on the three counts.
Peter Wright QC, prosecuting, said the case against Devine was "very straightforward", saying Devine made the fraudulent claims "with a view to gain for himself, or with an intent to cause loss to another - the public purse".
He said the Green Book guide for MPs made clear that when claiming expenses MPs should be guided by the principles of "selflessness, integrity, objectivity, accountability, openness, honesty and leadership".
Devine was granted unconditional bail by Mr Justice Saunders, the trial judge, after the six man, six woman jury's verdicts.
During the trial Devine claimed his former office manager Marion Kinley paid herself more than £5,000 from his staffing allowance without his knowledge.
After the verdict Ms Kinley said: "Justice has been done. The jury obviously saw through Mr Devine's lies. For legal reasons, I will not be making any further comment at this time."
Simon Clements, head of the Crown Prosecution Service special crime division, said: "Jim Devine submitted invoices for services that he had neither paid for nor received. In doing so, he took advantage of the trust that had been placed in him by virtue of the public office he held.
"Submitting a false invoice is plainly dishonest, regardless of why it has been done or who has done it. We say there is no excuse for such conduct and, with today's conviction, it is clear the jury agreed."
Under cross-examination Devine had denied "wholly deliberate deceit" in submitting his Commons expenses.
Cash in hand
He claimed he was advised, by another Labour MP and by expenses officials at the Commons Fees Office, that he was allowed to use money in his communications allowance to cover staff costs.
Devine says he did not benefit personally from the claims. He says the £5,505 he claimed for stationery was used to pay a woman, referred to in court as "Miss X", for six months' work, cash in hand, but he would not name her.
The trial has been told he was concerned she would be investigated for benefit fraud.
He says he did have a cleaner - called Larissa - but paid her cash in hand and not been able to contact her. He said she "ran for the hills" when he was charged.
The prosecution's case was that neither the cleaner, nor Miss X, existed. Mr Wright said: "It's as much a figment of Mr Devine's imagination as a great deal of this case is."
He added: "Each and every time that any civilian witness or MP is brought along to give an account - it doesn't bear much of a resemblance to his version of events."
He said the former MP had been going through a divorce and had legal bills to pay but Mr Devine denied having financial problems at the time.