The New Zealand international has penned a two-year deal and will play in The Bantams` friendly against Barnsley on Saturday.
Paston played for Napier City Rovers back in New Zealand but sealed a contract with the Yorkshire club after good performances on the side's tour of Scotland.
All Bradford players will be keen to succeed next season after chairman Gordon Gibb offered up to £1.5 million in financial incentives for promotion.
David Wetherall was quick to explain that it was not the playing staff who requested the new improved bonus system.
"It is not a case of players wanting to bleed the club dry here. If we under-achieve, we get nothing," the defender told the Bradford Telegraph & Argus.
"If we have an amazing year, and it would be a fantastic, unbelievable year - then the players will be rewarded for it.
"We are not getting paid for failure."
Manager Nicky Law has welcomed the bonus scheme and feels it will help get the best out of the squad.
"If you pay people for failure then that is what you are going to get," he said.
"The bonuses that have been proposed to players are good ones and they will be rewarded for being successful."
