Alan O'Neill, 42, was charged in March after his first wife learned of his second wife through a Facebook "people you may know" notification and alerted authorities.
The second woman's profile photo showed her with O'Neill, dressed in fancy clothes and standing near a wedding cake, reported Friday.
O'Neill, who was accompanied to court by the second woman, told Superior Court Judge Beverly Grant he never meant to commit a crime.
"I've never done anything intentionally wrong in my life," he said Thursday.
O'Neill was spared jail time but will be on probation for a year. The charge is a gross misdemeanor.
He has annulled his second marriage and is divorcing his first wife.
His first wife, though, seems to have forgiven him. She wrote a letter of support, saying that the media coverage has been enough punishment.
"He just made a bad decision that hurt a few people's feelings and (brought) embarrassment to himself," she wrote.
O'Neill's lawyer, Philip Thornton, told the judge his client tried to get a divorce from his first wife before he married the second one. O'Neill trusted a neighbor to process his divorce through Lincoln County, but the neighbor didn't file the paperwork, Thornton said.
"Mr. O'Neill failed to follow through on that," Thornton said. "He is extremely embarrassed and remorseful."
O'Neill's future as a Pierce County jailer remains in question, however.
He is on unpaid leave. Sheriff Paul Pastor, who oversees the jail, will evaluate the results of an internal affairs investigation before deciding whether to allow O'Neill to come back to work, sheriff's spokesman Ed Troyer said.