The Straits Times reported that Tan got to know Ms Tan in 2000 while he was working as a chief executive officer of an events management company.
They entered into a relationship the following year.
Tan told Ms Tan about his first marriage but assured her that he intended to file for separation and even produced documents to show that he was filing for divorce, said Deputy Public Prosecutor Elaine Liew.
Tan chose to marry Ms Tan in New Zealand because he knew that he could not register their marriage in Singapore.
He also claimed he had unresolved "tax issues" in Singapore that were linked to his first wife.
Tan will begin his sentence on January 7 next year after his lawyer told the court his client wished to spend the holiday season with his children.
Under Singapore law, it is illegal for married persons to marry again in Singapore or elsewhere, and they could be convicted even if the second marriage was just a customary one.
Tan could have been jailed up to seven years and fined for bigamy.