The England under-21 starlet came off the bench with 17 minutes remaining and converted his one and only chance in the 86th minute after Andy Cole's effort eight minutes earlier had looked like sending Glenn Roeder's men home empty-handed.
However, while a point against an in-form Blackburn would normally be considered an excellent result - especially given our current situation - there was still an over-riding sense of disappointment after a second half display in which Hammers missed a number of glorious goal-scoring chances after fighting back from a disastrous start to the afternoon.
Hammers had suffered a blow before the game when Fredi Kanoute, who had made a relatively impressive return to action in the Boxing Day draw with Fulham just two days ago, was forced to withdraw - presumably after suffering a reaction to his first 75 minutes of Premiership football in almost three months.
Perhaps more surprising - although in all honesty quite sensible - was Roeder's decision to leave out Defoe. The 20-year-old striker has had a tough time of it in recent weeks, being forced to carry much more responsibility than his young shoulders should have to bear.
Also missing from the starting line-up was Tomas Repka, sent off for persistent dissent in the last minute on Thursday. His absence meant a recall in the centre of defence for Gary Breen - making his first start since November 6 - as Roeder attempted to add slightly more defensive strength to his team and fielded Ian Pearce as a lone striker with support from Joe Cole and Trevor Sinclair.
With just three minutes gone, though, the Hammers boss saw his problems go from bad to worse, as Blackburn were gifted a simply amazing opening goal that goalkeeper David James certainly won't want to see again in a hurry.
As Egil Ostenstad fed Damien Duff some 20 yards out, there appeared to be no worry as the young Irish winger fired in a weak low shot straight at the centre of the goal. It appeared to be an easy catch for James, but the Hammers keeper took his eye off the bounce of the ball and allowed it to slip from his grasp and roll agonisingly over the line.
The goal understandably stunned the visitors, and memories of last season's horrific 7-1 drubbing at Ewood Park began to resurface as Rovers attacked at will and came close to adding further goals that could have killed the Hammers off in the first 20 minutes.
Duff almost turned provider when he drove a superb volleyed cross into the six yard box that was just inches from being stabbed home by the outstretched boot of Andy Cole, while the former Manchester United striker went even closer a few minutes later when his header from close range was tipped on to the bar by James.
After surviving those scares, though, Hammers began to display some of the fighting spirit and determined character that has been apparent all season - even if results have suggested otherwise.
On 23 minutes, the equaliser arrived at the end of our first real attack of any note. Joe Cole broke free on the counter-attack and fed the ball to Steve Lomas, whose low shot from the edge of the area took a deflection off the boot of Taylor and looped up over Brad Friedel into the corner of the net.
That provided a noticeable boost for Roeder's men, who then found some passing rhythm with Joe Cole looking particularly impressive in an attacking central role just behind Pearce that is surely his strongest position.
However, it was the other Cole on the pitch, Andy, who went closest to adding a second goal just before half-time, when he turned well on the edge of the area and fired in a stinging low shot that James - trying his hardest to redeem himself - managed to tip round the post.
At the start of the second half, Blackburn boss Graeme Souness introduced Dwight Yorke as a third striker, but his tactics only succeeded in providing Hammers with more possession in the opposition half that should have led to more goals, as they dominated in an amazing 20-minute spell.
With the immaculate Michael Carrick once again pulling the strings from the centre of midfield, Roeder's men found time and space against Rovers' back-three and wasted a glorious opportunity to take the lead in the 53nd minute when Lomas' low cross from the right reached Pearce, who dragged his shot wide with only Friedel to beat in the penalty area.
Edouard Cisse - back after a bout of Chicken Pox - then curled a 25-yarder just over before beating the offside trap in the 59th minute and lobbing just wide from an acute angle.
A minute later, it was Trevor Sinclair's turn to leave the travelling Hammers fans holding their head in despair, as he latched on to Carrick's quick free-kick but shot straight at Friedel from just 12 yards out.
Carrick was again the provider two minutes later, after his neat turn on the edge of the area set up Pearce, but the makeshift striker shot just wide of the post again, and you began to get that familiar feeling that Hammers would be made to pay for their errors in front of goal.
Sure enough, with just 13 minutes remaining, Blackburn finally found a breakthrough after weathering the storm, as Tugay's slide-rule pass released an unmarked Cole, whose clever touch took the ball past the dive of James and allowed him to tap into an empty net.
It was a case of 'same old story' for claret and blue
followers but, once again, Roeder's men showed just what they
are made of to find a way back into the game when the door seemed
to be shut.
Soon after Cole's goal, John Moncur came on for the exhausted
Cisse, and the veteran midfielder's one notable contribution
with four minutes remaining was to send over a deep cross from the
left that Pearce nodded down into the six yard box, where Defoe
pounced to beat Todd to the ball and stab past Friedel.
The relief and delight on the faces of the players was clear for all to see, and Hammers can now go to Charlton Athletic on New Year's Day confident of finding that elusive victory that can't be too far away if the performances carry on in this vein.
"I think this is a really important point for us and it was the least we deserved" said a relieved Glenn Roeder at the final whistle.
"Had we not got an equaliser, the lads would have been very down. But they have been down before and managed to pick themselves up, so I had no doubt they could do it again. We have shown a lot of character and we can now go to Charlton on Wednesday confident of getting a good result."
*WE ARE CURRENTLY EXPERIENCING TECHNICAL DIFFICULTIES THAT MAY HAVE PREVENTED SOME SUPPORTERS FROM ACCESSING THE LIVE AUDIO COMMENTARY. WE APOLOGISE FOR ANY INCONVENIENCE CAUSED AND HOPE TO HAVE THE PROBLEM RECTIFIED SOON...