The son of manager Paul has been struggling with a thigh injury but came on in the 67th minute and then scored a stunner in the 81st minute.
Watford bossed the first half but Troy Deeney saw his penalty saved by Matt Gilks, while Marco Faraoni struck the frame of the goal twice.
But Blackpool were much improved after the break and Ince's fine finish at the end of a mazy 81st-minute run made it four wins out of five for the Seasiders.
The Tangerines are ahead of QPR on goal difference on 13 points. Harry Redknapp's side also enjoyed a 1-0 success as they won at QPR in the early game.
Nottingham Forest were on course to join them on 13 points when Andy Reid put them in front at Wigan after just eight minutes but a Shaun Maloney penalty and a Jordi Gomez goal before half-time gave Owen Coyle's side all three points.
Leicester City also remain on 10 points after they fell 2-1 at Charlton and Burnley are now third also on 10 points but ahead of Leicester and Forest on goal difference thanks to an impressive 3-0 win at Derby. First-half goals from Danny Ings and Sam Vokes put the visitors in the box-seat and after Tom Heaton saved a Johnny Russell penalty, former Derby defender Jason Shackell clinched the points with a 73rd minute spot-kick.
Championship newcomers Bournemouth occupy the final play-off spot after Brett Pitman scored the only goal of the game at Doncaster.
Leonardo Ulloa hit his fourth goal in five Championship games for Brighton to deny 10-man Millwall a first league win of the season in a 1-1 draw at the Amex Stadium.
Jordan Rhodes scored his second brace of the week as Blackburn saw off Bolton 4-1 in an enthralling Lancashire derby at Ewood Park.
Reading returned to winning ways after securing a late 1-0 victory at beleaguered Yeovil. In the first ever league meeting between the sides, Adam Le Fondre's penalty 13 minutes from time handed the Royals their first Championship win since the opening day.
Chris O'Grady and Martin Pedersen grabbed first-half goals as Barnsley beat Yorkshire rivals Huddersfield 2-1 to record their first victory of the season.
Middlesbrough came from behind to salvage a draw with Sheffield Wednesday. Boro dominated for long spells but fell behind when Michail Antonio stabbed home from a corner. The home side levelled quickly after the break through Mustapha Carayol but despite creating plenty of chances they could not force a winner.
Christophe Berra marked his first appearance since a close-season move from Wolves with a crucial goal for Ipswich in their clash with Birmingham which ended 1-1 at St Andrew's. Birmingham, however, bounced back to earn a draw with a 76th-minute goal from another Scotland international, Chris Burke, on his third start of the season.
Leeds 0 - 1 QPR
Barnsley 2 - 1 Huddersfield
Birmingham 1 - 1 Ipswich
Blackburn 4 - 1 Bolton
Blackpool 1 - 0 Watford
Brighton 1 - 1 Millwall
Charlton 2 - 1 Leicester
Derby 0 - 3 Burnley
Doncaster 0 - 1 Bournemouth
Middlesbrough 1 - 1 Sheff Wed
Wigan 2 - 1 Nottm Forest
Yeovil 0 - 1 Reading