Harewood, who has completed the formalities of a three-month deal, is expected to join fellow newcomer Zurab Khizanishvili in the squad for the trip to East Anglia.
Harewood, 30, who will wear the number 10 shirt, arrived at the club's training headquarters on Friday morning to put pen to paper.
Chris Hughton is likely to restore the bulk of his senior men for the encounter after resting them against Peterborough, although he will be without the injured Joey Barton (ankle) and the suspended Danny Guthrie, while Danny Simpson (also ankle) remains a major doubt.
Shola Ameobi (foot) will be sidelined for some time yet but while Jonas Gutierrez (hamstring) will not make Saturday's game, he is expected to resume training on Monday.
It is sure to be an emotional afternoon as both sets of supporters pay tribute to the late Sir Bobby Robson, with the north stand at Portman Road to be officially renamed after the manager before the game.
Kick-off on Saturday is at 5.30pm.