After putting pen to paper on the new deal, the 21 year-old winger will now stay with City until the Easter Monday match at Swindon Town on 21 April 2014.
Under Football League regulations regarding emergency loan deals, this is the longest the club could have extended Reach's loan move by.
Reach's previous loan contract with City expired on Sunday after the club had already extended it once before back in February.
Subject to the loan extension being cleared by the Football Association and the Football League, Reach will now be able to take part in the Bantams' home fixture with Walsall this Tuesday (25 March 2014).
Bantams boss Phil Parkinson: "It is obviously good news for us to see Adam staying with the club.
"He has been an excellent acquisition for us and we've enjoyed working with him so far. Adam is really enjoying his football here and we're delighted to keep him with us.
"He knows how we play now and he offers us a real threat down that left flank.
"He is an intelligent footballer as well as having real quality."