Substitute Craig Farrell scored with his first touch against his former club as Telford engineered a late winner at York.
Farrell had only been on the pitch two minutes when he reacted first to a shot which came back off the post.
York had most of the chances, Jason Walker firing over from close range and then shooting wide after Lanre Oyebanjo's pass.
But Farrell made his old club pay with an 87th-minute winner.
Telford's first win made up for their 1-0 defeat in their campaign opener at Cambridge last Tuesday night.
AFC Telford United manager Andy Sinton told BBC Radio Shropshire:
"The boys have executed the plans. Tactically we were spot on.
"Two games in and full credit to my players. They've been outstanding.
"We're under no illusions. The league we're in now is different to the one they left seven years ago. It's a professional league now, so we're at a disadvantage."
York: Ingham, Oyebanjo, Smith, McGurk, Meredith, McLaughlin, Boucaud (Kerr 76), Moke (Fyfield 64), Blair (Reed 47), Walker, Chambers.
Subs Not Used: Parslow, Potts.
AFC Telford: Young, Salmon, Killock, Preston, Newton, King (Meechan 74), Davies, Valentine, Trainer, Reid (Samuels 69), Brown (Farrell 84).
Subs Not Used: L Evans, Adams.
Ref: Tony Harrington (Cleveland).