The visitors defended well and limited Spurs' opportunities before Soldado coolly slotted home his third match-winning penalty of the season with the victory moving Tottenham back into the Barclays Premier League top four.
Despite not being as defensively minded as West Ham had set out when they won 3-0 at Spurs earlier in the month, Hull's containment plan worked to great effect in the first 45 minutes.
Paulinho hooked a Lewis Holtby free-kick just over Steve Harper's crossbar as the home side created the first clear-cut opportunity of the game after 12 minutes and Townsend then came close to continuing his fine goalscoring form with a dipping effort from 25 yards which Harper pushed behind for a corner.
The Tigers did well in the early stages, troubling Spurs and forcing a number of corners whilst restricting the service to the likes of Soldado at the other end.
Hugo Lloris was called into action for the first time shortly afterwards but George Boyd's long-range effort was straight at the France captain with the returning Tom Huddlestone flashing a rising volley over the bar as Andre Villas-Boas cut an increasingly frustrated figure on the touchline.
Vlad Chiriches danced through a couple of challenges before being fouled by Liam Rosenior, who was booked for the challenge as the half ambled towards a conclusion and the resulting free-kick was rolled into the path of Kyle Walker whose rasping effort was pushed clear by Harper.
Spurs looked sharper at the start of the second half and Soldado came close to opening the scoring but could only scuff a shot at Harper after the Spaniard had been slipped in by Townsend.
The former Valencia striker then went down in the penalty area under pressure from Paul McShane but referee Michael Oliver was unmoved.
Oliver did give a free-kick to Hull as they broke forward, booking Chiriches for bringing down Sagbo after the summer signing from Evian had brushed past him.
Hull continued to keep men behind the ball and frustrate Spurs as Villas-Boas introduced Christian Eriksen and Jermain Defoe from the bench as he looked to inject fresh impetus in to his side.
The deciding goal came from the penalty spot in the 79th minute as Ahmed Elmohamady was adjudged to have handled a Jan Vertonghen cross from the edge of the box.
Bruce was livid with the decision as Elmohamady was in close proximity to Vertonghen but the ball struck him on the hand and Soldado stepped up to convert his third penalty of the season.
Townsend then required lengthy treatment after he crashed into the advertising hoardings and fell into the photographers' pit behind the Hull goal and returned with a bandaged wrist.
Hull substitute Robbie Brady hit a set-piece straight at Lloris before Huddlestone arrowed an injury-time free-kick wide of the goal as Spurs held on to return to the Champions League berths.