The Seasiders fully deserved a replay at Bloomfield Road after they cast aside poor league form which had seen them stumble to five straight defeats.
And it was the visitors who almost stole a shock lead in the third minute when former City favourite Simon Grayson put Keigan Parker through for a one-to-one with the keeper, but Kevin Pressman stood his ground to block the shot.
It was to prove a costly miss for Blackpool fell behind in the 12th minute through a cruel own goal when Rob Edwards tried to clear a Gareth Williams free-kick, but instead managed to guide a header from eight yards into his own net.
The Seasiders repelled sustained pressure and levelled on 31 minutes when the home defence failed to clear Parker's free-kick which Peter Clarke headed home at the far post.
Leicester dominated the second half but were unable to break down Blackpool and on 65 minutes Craig Levein made a double substitution sending on debutants Mark De Vries and Alan Maybury in place of Chris Makin and Martin Keown.
But it was Blackpool who stunned the home crowd by taking a 78th minute lead when Keith Southern stole the ball from a hesitant Dion Dublin and surged into the penalty area before calmly slotting the ball beyond Pressman.
The Foxes equalised within four minutes when David Connolly crossed from the byline for Williams to score with a thunderous shot from six yards which ricocheted off the near post and into the back of the net.