The 19-year-old from Republic of Ireland has enjoyed a positive impact in Kevin Wilkin's defence since he checked in on a temporary deal from the League Two club.
The central defender made his debut in the 2-0 FA Trophy exit at Solihull Moors before Christmas and has since started in the Bucks' three consecutive National League North draws against Chester, twice, and Spennymoor.
Another month with Telford stands to see O'Brien available for up to seven more fixtures as Wilkin's side try to salvage their step two status. The Bucks are currently 12 points adrift of safety.
One of the clubs they trail by 12 points are Buxton, who Telford visit for their next clash on Saturday.
Wilkin was pleased to have captured the loan of highly-rated O'Brien, who previously had a short spell at Watford. The defender is Dublin-born but was raised in the United States.
He has been part of a defence alongside the rejuvenated Harry Flowers, who has scored twice in two games and caught the eye with positive displays, including as captain last time out against Spennymoor.
O'Brien is currently filling in for the absent Matty Brown (groin) and Jordan Piggott (knee), who are both missing through injury.
The duo have not featured since the last-gasp Kidderminster defeat in November.