A Schwarzer mistake gifted the visitors their opener but inventive work from substitute Sigurdsson and former Fulham man Dempsey, the striker grab two goals in a dominant win
Sandro and Jermain Defoe were the matchwinners for Andre Villas-Boas' side as a hopeful 35-yard strike from the midfielder found its way past Mark Schwarzer, before the 30-year-old striker tapped home Gylfi Sigurdsson's excellent assist, and raced onto Clint Dempsey's through ball to slide home his second of the game.
Perhaps the biggest talking point of a slow, cautious first period was Gareth Bale's yellow card for diving as he theatrically tumbled after dribbling past Steve Sidwell.
That aside, the away team created the first genuine chance of the game, as Dempsey – roundly booed on his return to Craven Cottage – spun his marker and sidestepped a second challenge on the edge of the box, before curling his left-foot shot just wide of Mark Schwarzer's post.
The hosts carried a threat down the right flank and Ashkan Dejagah delivered a dangerous cross that fell to Kerim Frei who should have at least tested Hugo Lloris from the edge of the box, instead firing well over.
Fulham's best opportunity fell to Mladen Petric, but Lloris reacted sharply to parry and hold onto a close-range shot, denying the Croatian his fifth goal of the season.
After Sascha Riether was replaced by Stephen Kelly courtesy of injury, Petric again found himself in ample room on the edge of the Tottenham box to fire a shot high and wide. With Bale's shooting similarly wayward at the other end, after incisive work from Aaron Lennon, it rather painted the picture of a game lacking quality.
Neither manager made a change at the break and though the home fans were briefly lifted from their seats as Dimitar Berbatov continued his one man mission to inject a touch of class to proceedings, it was Sandro who broke the deadlock on the 56th minute.
The Brazilian collected the ball near the halfway line and after assessing his options, struck a powerful, if ambitious, 35-yard drive that deceived Schwarzer, who could only parry his effort into the side-netting of his goal.
Spurs began to find their rhythm and although a Bale run and shot from the left side of the penalty box forced Schwarzer into an alert stop at his near post, the Welshman grimaced and clutched his hamstring forcing Villas-Boas into a second change as Sigurdsson entered the play. It was the third injury-induced substitution of the match.
Fulham pushed forward, but found little joy and it was the Icelandic substitute who displayed exceptional trickery on the 72nd minute to glide past Philippe Senderos in the box and square for Defoe to sweep home and double the visitors' lead.
Barely five minutes later, Defoe had his second sight of goal as Dempsey weighted a clever through ball into his path. With only Schwarzer to beat, Defoe made no mistake, guiding the ball into the bottom-right corner to seal three points for Spurs.
The Cottagers mustered a couple of half-chances but Lloris dealt ably with the threat, most notably from a low Hugo Rodallega header, as Spurs saw out the game confidently. It was their sixth consecutive Premier League win over Fulham and although it was far from a classic, Villas-Boas has Spurs moving in the right direction.