Fearing the worst to begin with, City's medical staff had the full details of the injury confirmed to them this Monday afternoon following a scan on Reid's injured knee.
The winger will now need surgery on the injury in the next couple of weeks once the swelling around his knee has gone down.
Reid had to be stretchered off at Bramall Lane last Saturday after catching his knee in the turf just before the half hour mark following a tangle with Sheffield United defender Tony McMahon.
The unfortunate news obviously ends Reid's interest in the rest of this season and comes shortly after left back James Meredith was ruled out for at least a couple of months with a broken bone in his right foot.
Bantams boss Phil Parkinson said: "We are obviously devastated for Kyel.
"We unfortunately felt at the time that Kyel had done something serious and we were fearing the worse over the weekend.
"It is a blow to us all to lose the services of someone like Reidy but we will give him all the support and care he needs to get back playing as soon as possible."