Initially signed on a month-long deal in August, O'Connor's stay at the Pirelli Stadium was quickly extended to the turn of the year after solid displays at right-back for the League Two club.
With that deal ending on Saturday after the 2-1 home win over Torquay, Brewers boss Gary Rowett had no hesitation in extending the 20-year-old's stay once again.
"Anthony has come in and made a big impact and we are delighted to have him with us now until the end of the season," Rowett told the club's official website.
"I think the main thing for Anthony has been to make sure he is playing regular football and you can see how much he has developed so far this season."
O'Connor has been virtually ever-present for Burton this season, making 32 appearances in all competitions to date.