Bent saw his weak spot-kick saved by Spurs goalkeeper Heurelho Gomes as goals from Robbie Keane and Tom Huddlestone condemned the Black Cats to a harsh defeat in north London.
Sunderland created plenty of chances in a lively and entertaining encounter, but their failure to take any of them proved crucial in the end.
Jordan Henderson had already wasted a decent early opening when Spurs broke the deadlock with their first chance of the game in the 12th minute.
Benoit Assou-Ekotto crossed from the left, Peter Crouch won a towering header, and while Craig Gordon saved Keane's first volley from the edge of the six-yard box, he was unable to prevent the Spurs skipper bundling home the rebound.
The entire Sunderland backline appealed for offside, but television replays suggested that Keane may have been level with full-back George McCartney when Crouch won his header.
Nevertheless, Sunderland went on to dominate the rest of the first half, and Andy Reid came within inches of an equaliser when his dipping long-range half-volley hit the right-hand upright.
The Black Cats wasted an even better opportunity for a leveller seven minutes after the break as Bent ruined his return to White Hart Lane.
Gomes sent the striker sprawling as he raced on to Steed Malbranque's through ball, but the Spurs keeper was only booked for the offence. That proved crucial, as he threw himself to his left to keep out Bent's weak side-footed spot-kick.
Gomes also saved from Steed Malbranque as the Black Cats continued to dominate midfield, but the visitors suffered another setback shortly after when Gordon was forced to retire with a shoulder injury.
Marton Fulop replaced him, but the Hungarian's first act was to pick the ball out of the net. Jermain Defoe rolled the ball into Huddlestone's path, and the midfielder crashed an unstoppable 20-yard drive into the net off the underside of the crossbar.
TOTTENHAM (4-3-1-2): Gomes; Corluka, King (Dawson 60), Woodgate, Assou-Ekotto; Palacios, Huddlestone, Jenas; Keane (Kranjcar 63); Crouch, Defoe.
Subs (not used): Alnwick (gk), Hutton, Bale, Bentley, Pavlyuchenko.
SUNDERLAND (4-5-1): Gordon (Fulop 67); Bardsley (Ferdinand 77), Da Silva, Turner, McCartney; Campbell, Richardson, Reid, Henderson, Malbranque (Healy 77); Bent.
Subs (not used): Nosworthy, Meyler, Reed, Murphy.