A fraudulent builder who ripped off dozens of New South Wales customers has been told he will go to jail if he offends again.

Matthew Geoffrey Rixon was given a suspended 18-month sentence and ordered to complete 300 hours of community work for failing to comply with an order to stop work.

He was banned from trading last year after being fined more than $72,000 for more than two dozen offences relating to dodgy building work.

Rixon had been advertising under both his own name and several aliases, as a building and fencing contractor, asking customers for large deposits and then failing to do the work or doing it to a poor standard.

He targeted customers in Sydney, the Newcastle region and the Hunter Valley.

He continued the fraudulent activity despite the ban using aliases including Matt Geoffrey, Matthew Ewing, Andrew Gough and Patrick Harding.

In May, Rixon was convicted of contempt of court for failing to comply with the order to stop trading.

Sentencing him, Supreme Court Justice Peter Garling said Rixon had breached the order shortly after it was made and on 24 occasions.

"In my view he set out to, and succeeded, in preying on unsuspecting home owners who at all times thought they were dealing with a properly licensed builder," Justice Garling said.

The conduct was "extensive, persistent and very serious", he said.

Justice Garling ordered Rixon to comply with the ban on trading and do 300 hours of community work as conditions for the suspension of his sentence.

"Let me make this perfectly clear: if you don't comply with the conditions, you will automatically serve the balance of imprisonment," the judge told Rixon.

Outside court, Rixon said much of the money had been repaid and there were "not enough words" to say how remorseful he felt.

NSW Fair Trading Minister Matthew Mason-Cox said his department had received more than 50 complaints from customers about unfinished and poor quality work carried out by Rixon.

"Mr Rixon deceived consumers into paying him illegal deposits then doing shoddy work or not doing any work at all," Mr Mason-Cox said.

"He had no scruples, often targeting the elderly and vulnerable."

Mr Mason-Cox said Rixon also allegedly failed to pay tradespeople, including subcontractors and apprentices, and he urged anyone who had previous dealings with him to contact NSW Fair Trading.