Ian Holloway's men went into Sunday's final fixture knowing victory would guarantee a top-six finish, but Swansea's failure to beat Doncaster ensured a point was more than enough for the Seasiders.
Nicky Maynard gave mid-table City a surprise first-half lead with a wonderful opportunist strike.
But Brett Ormerod levelled nine minutes after the break to earn the hosts a share of the spoils.
Blackpool are now just three games away from securing promotion to the top flight for the first time in 40 years.
They will take on Nottingham Forest over two legs, with the winner meeting Cardiff or Leicester at Wembley on May 22.
With DJ Campbell overcoming a bug, Holloway had the luxury of naming an unchanged starting XI.
City caretaker boss Keith Millen made just one change for his final game in charge, with Ivan Sproule starting in place of the injured Danny Haynes.
In his programme notes, Holloway called on his team to "go out and give it their all" - and they almost made the perfect start as Charlie Adam drilled a shot narrowly wide of Dean Gerken's right-hand post in the third minute.
City offered little as an attacking force early on, but they took the lead in the 16th minute courtesy of a moment of magic from top scorer Maynard.
A long ball was flicked on to the former Crewe striker and he spotted Blackpool goalkeeper Matt Gilks off his line before finding the net with a dipping half-volley from 30 yards.
Ormerod forced Gerken into action at his near post as the Seasiders looked for an immediate response.
And they almost levelled in the 23rd minute as Vaughan's inswinging corner was clawed off the line by Gerken.
Campbell twice shot wide from promising positions and Seamus Coleman also failed to hit the target following a powerful run from right-back.
Yet City, who lost Cole Skuse to injury on the half hour, held on to their lead with relative comfort going into the interval.
Campbell was withdrawn four minutes into the second half, with Stephen Dobbie coming on in his place.
And the hosts drew level five minutes later as Ormerod powered home a header from Adam's curling free-kick.
Gerken made a fine stop to deny Ormerod a second goal in the 59th minute after the striker had beaten the offside trap.
At the other end, the dangerous Maynard prodded over the bar after shrugging off the attentions of two Blackpool defenders.
Although City were a threat on the counter-attack, Blackpool remained in the ascendancy and went agonisingly close to taking the lead with 18 minutes to go as Dobbie's thunderous 25-yarder was tipped over by Gerken.
Despite some frantic late pressure, the hosts were unable to find a breakthrough and they needed Gilks to be alert to keep out a late strike from Jamal Campbell-Ryce.
But it mattered not as news of Swansea's draw filtered through from south Wales, sparking wild celebrations among the home faithful.