Serge Aurier's 40th-minute cross-shot and Heung-min Son's late effort provided Spurs with all three points against a poor Brighton.
The hosts had to wait, but Son sealed the deal in the 88th minute.
Tottenham dominated the game from start to finish, enjoying the large majority of possession but struggling to break down a deep Brighton defence.
Brighton played as many would have expected, they sat deep and waited to catch Spurs on the counter-attack.
However, Brighton lacked the composure and quality needed to grab a point at Wembley as they only managed a handful of shots on goal.
Slow start for Spurs
Tottenham enjoy the large majority of the possession in the first half. however, struggled to create any clear opportunities on goal.
The visitors set out to defend as do a lot of teams traveling to Wembley. With just about every man behind the ball, Spurs found it hard to find a breakthrough.
However, Spurs did not help themselves. In the weekend's 5-1 battering of Stoke, we saw a fluent Tottenham side playing with a high tempo.
Through Heung-min Son working the wing, providing width and pace - Spurs proved deadly on the attack.
Tonight, Spurs reverted back to playing through the middle of the park. Their play replicated the flat atmosphere within the stadium.
Fluke from Aurier
Spurs had been by far the better of the two sides, yet they had not really had a clear break on goal.
The deadlock was broken in the 40th minute when a Serge Aurier cross looped over Australian goalkeeper Matthew Ryan.
Aurier was initially fouled as he crossed the ball in. However, referee Bobby Madley allowed the advantage to be played as the ball lobbed the helpless goalkeeper.
Nevertheless, a fine strike from the Ivorian, whether he meant it or not surely will be asked after the game but he will take it - his first goal in Spurs colours.
The strike had a great amount of resemblance to Harry Kane's opener against Everton back in September.
A combination of good-luck and great refereeing.
On my head Son
Spurs scored another late in the half goal as man of the moment Son bagged his fourth in four games.
Son latched on to a Christian Eriksen free kick. His header was deflected in by Davy Pröpper and past goalkeeper Ryan.
The South Korean has provided the difference for Spurs in the past few weeks, grabbing himself a handful of goals, assists and man of the match awards.
More joy for Spurs
After the interval, Spurs enjoyed the same high percentage of possession - this time with more purpose.
Tottenham, although dominant in the first-half looked like a different team in the second 45. Showing much more intensity and urgency when on the ball.
It was clear that boss Mauricio Pochettino had insisted that a one-goal advantage may not be enough against the Brighton team looking to catch the hosts on the counter.
Brighton's only real chance on goal came through Tomer Hemed's snapshot on goal which was struck straight at Spurs' captain. Hugo Lloris.
Harry Kane, chasing Alan Shearer's record of 36 goals in one calender year looked desperate to get on the scoresheet.
He bullied Christian Eriksen off a free-kick but his effort cannoned off the post - much to the Englishman's dismay.
Steady return for Lamela
Forgotten man Erik Lamela made his first start in 14 months in replacement of the rested Dele Alli.
From the first whistle, Lamela looked positive and keen to get on the ball.
Predictable at times, yet a return that will have impressed Pochettino as he provided Tottenham something different going forward in comparison to Dele.
However, the Argentine was replaced in the 75th minute by Dele Alli - who has looked off the boil in recent weeks.