Liam Thomson married a woman at the Burgh Chambers in Galashiels on May 7 last year when he was already married to another woman.
The 50-year-old also admitted falsifying a divorce extract document and presenting it to a registrar on February 8 last year.
Selkirk Sheriff Court was told that Thomson's first wife was shocked to find out he had married again as there had been no divorce proceedings although they were separated and had no contact.
Sheriff Peter Paterson said falsifying a divorce document was a very serious matter and imposed a six months prison sentence.
Defence lawyer Mat Patrick immediately lodged an appeal.
Thomson was released on bail until the Appeal Court hearing can take place in Edinburgh.