Henderson, who has won one cap for England’s senior team, will undergo a medical at Melwood on Wednesday.
It is understood that the deal is worth £20million in total, with Reds striker David Ngog joining the Black Cats and Liverpool paying up to £13m with add-ons.
Henderson will fly out with the England U21 squad for the forthcoming European Championships once he has completed his medical, while Ngog has traveled to the North East for his medical at the Stadium of Light.
Ngog arrived at Liverpool from French side PSG for £1.5m in 2008, making 63 appearances to date. His departure frees up a spot for young English striker Connor Whickham to arrive from Ipswich Town.