Souness, booed every time he went to the touchline by the home fans, saw his team twice take the lead only to be pegged back by enterprising Blackburn.
Kieron Dyer gave the Magpies the perfect start after just six minutes, racing on to Laurent Robert's perceptive pass to coolly beat Brad Friedel.
Robert, recalled to the starting line-up despite some controversial public comments about his manager during the week, then scored a tremendous free-kick in the 34th minute after Paul Dickov had earlier equalised for Rovers.
However, home centre-back Andy Todd levelled matters nine minutes after the break and that was how it stayed despite a late flurry of chances.
Afterwards Souness said: "It was a difficult game today, Blackburn were very physical and positive in their approach.
"It was the same old story for us as we got in front but conceded some poor goals."
Meanwhile, Blackburn, who made it just one defeat in nine games with this result, had plenty of chances to secure a much-needed victory.
Rovers boss Mark Hughes paid tribute to his team's character after they twice recovered from going behind.
He said: "The lads showed a lot of resolve and determination, we were up against a very good team and we put up a very good performance.
"Overall I think that we were the side more likely to win the game."
Blackburn almost took the lead before Dyer struck. Steven Reid's powerful header cleared off the line by a well-placed Robert.
The Frenchman then sent Dyer in behind a static Blackburn defence and he had acres of space to drill a shot into the far corner.
Stung, Rovers tried to reply immediately and captain Barry Ferguson shot wide from a free-kick and Gary Flitcroft nodded a terrific looping header inches over Shay Given's crossbar.
Dismal defended has been blamed for Newcastle's recent poor run and their defence was caught napping for Blackburn's equaliser after 26 minutes.
As the Magpies lined up to defend a free-kick, Dickov drifted in to space 12 yards from goal. The quick-thinking Ferguson picked him out and the diminutive striker buried a first-time shot into the net.
Shortly afterwards the home fans called for Robbie Elliott to be given his marching orders after he dragged down Jonathan Stead as he headed for goal, but referee Matt Messias chose yellow instead of red.
Matters got worse for Blackburn when they then went behind to a stunning 30-yard Robert free-kick - although questions must surely be asked of the ease with which it beat Friedel.
At the break both managers shuffled their packs. Hughes sent on David Thompson for Reid whilst the ineffectual and unfit Patrick Kluivert was replaced by Shola Ameobi.
It was the Blackburn change that had the most immediate effect as Rovers fashioned three golden chances in the space of ten minutes.
First, Dickov set up Brett Emerton for a great opportunity, but just 17 seconds after the interval the Australian winger could only shoot weakly at the advancing Given.
Thompson then found space on the right to cut back to Ferguson and his drive was again well saved by the Newcastle goalkeeper.
The equaliser Blackburn's performance merited eventually arrived and it came courtesy of an unlikely source.
Todd, isolated from the first team in the latter days of the Souness era, suddenly found himself alone in the penalty area and was on hand to tuck home when Given could only parry a fierce shot from distance.
Both sides had their chances as the final whistle approached - the best falling to Craig Bellamy, but he dragged the ball wide when well placed.
There was even time for referee Messias to limp off and be replaced by Uriah Rennie for the last five minutes.
Then, in the dying seconds, Thompson thumped a shot from the edge of the box but Given managed to scramble it behind to ensure the game finished level.