Alan O'Neill's first wife saw a photograph of him on the 'People You May Know' section of the social networking site in which he was dressed smartly and standing with another woman next to a wedding cake, reports Washington's News Tribune.
Pierce County Superior Court judge Beverly Grant handed down a suspended sentence for the gross misdemeanor offence.
O'Neill's attorney Philip Thornton said that his client was "extremely embarrassed and remorseful" and had never intended to commit bigamy.
Explaining that O'Neill had left the divorce from his first wife in the hands of a neighbour who never filed the paperwork, Thornton added that the 42-year-old has annulled his second marriage, and still plans to divorce his first wife.
O'Neill is currently on unpaid leave from his job as a corrections officer, and a sheriff's spokesman said that the results of an internal investigation will be evaluated before a decision is made on whether he can go back to work.
His first wife wrote a letter to the court in which she said she felt her husband "just made a bad decision that hurt a few people's feelings and [brought] embarrassment to himself", and expressed her opinion that coverage of the case had been embarrassing enough for him.