With eight minutes remaining, midfielder Sessegnon struck after a corner as the visiting side’s pressure finally told.
In the third minute of stoppage time Bendtner capitalised on the break to give Steve Bruce his first win in four matches, leaving the Trotters in the bottom three.
Worryingly for the home side they have now lost seven home league matches in a row, five this season, their alarming slide only punctuated by a win at fellow basement boys Wigan and a freak 4-0 opening-day thrashing of QPR.
Until conceding they had defended well though, with a lack of spark up front their most notable shortfall. Sunderland were rewarded for their patience and laudable attempts to win the game when a draw would have been sufficient.
The first half could best be described as uneventful, with both sides defending stoutly but attacking with little ambition or accuracy.
With the exception of Bolton’s Darren Pratley – who in addition to his crisp passing put a low shot just wide when he should have scored – neither midfield had much of an impact.
The Trotters started brighter, initially showing more going forward with David Ngog linking well with Kevin Davies, but Pratley’s 13th-minute effort after smart play from Ngog was all they had to show for it, although the possibility of a clean sheet would have encouraged Owen Coyle, whose side have the worst defensive record in the division with 24 conceded in nine games so far.
The scrappy half hour that followed saw Sunderland regain some territory, wining a selection of set-pieces, two of which yielded their only real opportunities: Sessegnon thrashed over when Sebastian Larsson’s corner landed to him at the far post, while John O’Shea headed into the side netting from a near-post ball by the Swede.
That was as adventurous as both sides got, with neither keeper forced into more than straightforward claims of hopeful long shots as the game drifted into the break.
Words were clearly had by both coaches as the second half started promisingly: seconds after kick off Martin Petrov fired straight at Simon Mignolet when found unmarked on the edge of the box, with Sunderland responding with an aerial assault that forced Jussi Jaaskelainen into action and yielded a pair of corners.
Sunderland were agonisingly close to opening the scoring when Sessegnon found Kieran Richardson unmarked: he was denied twice by brilliant blocks, first from Dedryck Boyata and then David Wheater off the rebound.
Wheater – who is keeping Zat Knight out of the team – justified his selection again as he intervened when Connor Wickham bustled through, the young striker growing into the match as Sunderland were beginning to dominate.
The hosts were defending frantically at times but there was a sudden switch in momentum just after the hour mark as Ngog was agonisingly close to giving Pratley a one-on-one: his headed knock-down was ahead of the midfielder.
It seemed to work in Sunderland’s favour though as they fashioned a trio of chances in quick succession. Sessegnon was denied by Jaaskelainen, while David Vaughan twice went close as Paul Robinson deflected his first effort wide and, after Jaaskelainen flapped at the subsequent corner, the Welshman shot over.
In the final quarter hour Sunderland were all over the Trotters as Wheater again earned his coin with a double block, from Wickham and Richardson, while Wickham hit the top of the woodwork with a cross-cum-shot after Ricardo Gardner was caught in possession by Larsson.
There was an air of inevitability about Sunderland’s goal on 82 minutes, although for once Bolton were ragged at the back as Larsson’s corner ricocheted around the box into the path of Sessegnon, who drilled a low finish past Jaaskelainen from close range.
Bolton rallied, with Kakuta going close with a fizzing drive from the edge of the box and Mignolet making himself big to deny Pratley after the former Swansea midfielder bullied his way past the visiting defence.
O’Shea made an injury-time intervention to deflect Wheater’s goal-bound header wide and, with the hosts committing men forward, a swift counter from the visitors saw Sessegnon find the unmarked Bendtner, who picked his spot to drill a low finish past Jaaskelainen to seal the win.