Owen Coyle's side looked on course to climb out of the bottom three after Martin Petrov's penalty was followed by a Billy Jones own goal to leave Wanderers firmly in control at the Reebok Stadium.
But Chris Brunt reduced the deficit with 15 minutes remaining and James Morrison netted a stoppage-time equaliser.
To make matters worse for Coyle's men, news soon filtered through from west London that relegation rivals Queens Park Rangers had beaten Stoke City with a late goal.
That agonising combination of results leaves Bolton two points adrift of safety with a trip to Stoke to come on the final weekend of the season next Sunday.
There is still hope for Bolton, however. If they win at the Britannia Stadium, then a QPR loss at Manchester City or two defeats for Wigan Athletic in their remaining fixtures would secure their Premier League status for another season.
While Bolton worry over their future, Albion coach Roy Hodgson could take heart from his players' spirited fightback in what was his final away game before taking over as England manager.
The hosts got off to a better start, with Chris Eagles firing an early shot just wide of Ben Foster's goal.
Veteran striker Kevin Davies has found his way back into Coyle's starting line-up of late but he failed to repay that faith when he blasted over from close range after David Ngog knocked on Petrov's cross.
Bolton had been creating most of the early pressure, but the Baggies were dangerous every time they ventured into the hosts' half and Adam Bogdan was called upon again to keep out Gareth McAuley's header from Brunt's corner.
Bogdan denied West Brom again four minutes later with a superb save with his feet that took Shane Long's close-range effort onto the post.
The breakthrough came after 24 minutes when Youssouf Mulumbu recklessly brought down Mark Davies in the area.
Petrov was the man to step up and he remained calm before finding the bottom corner, just out of Foster's reach after the West Brom goalkeeper guessed correctly.
Davies could certainly have done better with his first-half chances but there could be little complaint when his 70th-minute header was superbly saved by Foster, who somehow got down low enough to palm the ball away.
Nerves were starting to creep in at the Reebok, but while Bolton have certainly had their fair share of bad luck this term, the most fortunate of goals put them 2-0 up in the 72nd minute.
Petrov's cross looked harmless until Liam Ridgewell panicked and smashed the ball off the helpless Jones, sending the ball spinning past Foster.
Bolton's joy was short-lived, however, as Brunt curled pulled one back three minutes later after Long's blocked shot fell into his path 12 yards out.
A slip by Tim Ream allowed substitute Simon Cox a chance to equalise, but his strike was saved by Bogdan.
Just as Bolton looked set to hold on, substitutes Cox and Morrison combined in stoppage-time, with the former chipping a ball in to the Scottish midfielder, who calmly slotted home with just 20 seconds remaining.
Source: AFP
Source: AFP