The visitors looked full of confidence in the early stages and Nathan Doyle was unfortunate with a rasping volley which flew for a corner off the head of Adam Yates.
ButVale soon responded in a wide open and physical contest with Tom Pope failing to hit the target with two close-range headers.
Visiting keeper Jon McLaughlin then made smart saves from Lee Hughes and Kaid Mohamed before Vale's pressure told in the 42nd minute.
Bradford left-back James Meredith scuffed an intended backpass and Hughes nipped in to round McLaughlin and slot the ball into an unguarded net.
The visitors equalised in the 59th minute after a brilliant piece of skill by Nahki Wells, who fired in the loose ball from two yards after his initial effort was saved.
But Vale's winner arrived seven minutes later when Loft struck a 20-yard shot from Hughes' lay-off and the ball took a deflection to beat McLaughlin high inside his left-hand post.