O'Brien has impressed at the heart of Simon Grayson's defence and has even scored one goal in his five appearances for the club.
"I'm happy to announce that we have agreed with Bolton to extend his loan until January," chairman Ken Bates told Yorkshire Radio.
"We've got him now until January 4 and then hopefully we'll be talking to Bolton to see if we can keep him beyond that. He's certainly been a great figure in the defence and he's enjoying it."
Source: PA