Patrick Roberts scored a quick-fire double as Tony Mowbray claimed his first away win as Sunderland boss.
The former Manchester City winger's goals came on 39 and 41 minutes and both were after individual acts of brilliance.
The second saw him dance past the challenge of two Reading defenders before slotting into the far corner with his left foot.
Both goals were assisted by Elliot Embleton, who came on just minutes earlier after Ellis Simms added to Sunderland's injury crisis.
They added another on 69 minutes after a fantastic passing move culminated in a great cross from Dan Neil and finish by Jack Clarke.