Blyth made their intentions clear from the start, playing five midfielders on a narrow pitch and closing and tackling their Premier League opponents in a bid to stifle their creativity.
Their intensity certainly seemed to take Blackburn by surprise as Sam Allardyce's team were reduced to pot shots for most of the opening half hour.
Even then they retained an air of danger and could have scored twice in a minute but for some outstanding defensive work.
First Kenny Boyle slid bravely in his own six-yard box to block a dangerous low cross from the right and then moments later, keeper Marc Bell was forced into an excellent save, low to his left, after Keith Treacy was given the space to hit a shot from 20 yards.
For the final 15 minutes of the half Blackburn turned the screw on the Conference North side, even finding the net once although Matt Derbyshire's deflected bicycle kick was correctly ruled out for offside.
The highly-rated striker missed an even better chance moments later, mis-kicking a high through-ball, before Vince Grella was gifted the chance of the half.
The Australian midfielder volleyed a Blackburn corner towards goal with power from six yards out, only he failed to beat the towering Richard Pell - one of four men on the goal-line - who got his head in the way of the ball.
Yet it was always going to be the case that if Blackburn found a way through then Blyth, who looked toothless with only Rob Dale up front, were all but dead and buried.
Then when the goal did come it was all the more frustrating for the hard-working Spartans that it was from a set-piece.
Carlos Villanueva's sweet free-kick from 25 yards was curled over Bell and into the far top corner of the goal in what was a flash of brilliance from the Chile international.
Rovers threatened to blow the game open, controlling the match for most of the rest of the half, but Blyth's impressive back four kept them at bay before they found the energy to provide a nail-biting last ten minutes.
With five minutes to go, the underdogs produced their best move of the game as good work from Dale got the ball to Alex Gildea whose back post cross was met by Andy Wright's boot but his volley somehow went wide from six yards.
Then two minutes later, Gildea himself found enough space at the front post to flick a Gareth Williams free-kick towards goal but again the Mark Bunn wasn't tested.
That was as close as Blyth came to forcing an upset but they will be happy enough with their effort, while Blackburn will be delighted to put cold Croft Park behind them and move on to Sunderland in round four.