Wednesday and Hull are set to meet at the national stadium tomorrow, with a place in the Premier League the prized for the victor.
The Owls finished the regular season nine points behind Hull and they go into the game as the outsiders.
And Waddle fears that his former side could struggle to get past Steve Bruce’s side, due to their experience.
“Carlos likes to play open, attacking football but, defensively, Wednesday are quite solid and quite well organised,” Waddle said.
“Their problem is that Hull are still virtually operating as a top-flight outfit. Steve Bruce has kept a nucleus of his Premier League team including Tom Huddlestone and Michael Dawson – relatively recent England internationals. My heart says Wednesday can do it at Wembley – but my head says Hull will be difficult to beat.”
Wednesday have upset the odds to even be in the play-off final, as they went into their semi-final tie against Brighton & Hove Albion as underdogs.
In that tie, the Owls won 3-1 on aggregate and they looked very impressive over the two legs.
Hull, meanwhile, had to edge past Derby County to book their place at Wembley.
The Tigers won 3-0 at the iPro Stadium, but Derby gave them an almighty scare in the second leg.
Derby race into a 2-0 lead at the KC Stadium, but Bruce’s men held on to move to within one victory of the top flight.