Tim Sherwood's men secured maximum points on Sunday thanks to a fine counter-attacking goal by Spain international Soldado.
The goal came just before the half-hour mark when Emmanuel Adebayor found the striker in the box with a slick pass and Soldado took the ball beautifully in his stride before calmly finishing into the far corner.
It was his first Premier League goal at White Hart Lane from open play and his first in nine games.
The struggling Bluebirds should have levelled soon after when Steven Caulker headed Craig Bellamy's corner against the crossbar from a couple of yards out with Hugo Lloris rooted to his line.
It was the north Londoners' fourth win in five Premier League home matches and victory also helped them cut the gap on fourth-placed Manchester City to four points.
Cardiff's seventh consecutive league defeat on the road leaves them one point and one place off the bottom of the table.
Struggle for control
Spurs struggled for control throughout the clash, with holding-midfield duo Paulinho and Mousa Dembele too often too deep and generally unconvincing.
Soldado's evident goal-shyness wracked the opening exchanges, the Spain striker wrestling unsuccessfully with two half-chances in three minutes.
Spurs twice sent Aaron Lennon in behind the Cardiff defence, with the England winger delivering accurate crosses both times.
First Soldado was unlucky not to direct his near-post header closer to the target but on the second Lennon cross he just overran the ball, failing to add any power as he nodded tamely at Cardiff keeper David Marshall.
Bellamy caught Andros Townsend in possession to race clear and send Fabio tearing into the Spurs box. As the Brazilian pulled the trigger though, Spurs skipper Michael Dawson produced a timely block.
Tottenham's aerial chances kept coming, with Dawson heading straight at Marshall after Kyle Naughton's well-worked free kick.
Dawson hacked a long-range shot well wide before glancing a near-post header wide of the static Marshall's far post after a pinpoint Naughton corner.
Tottenham ended a slight lull with a devastating counter-attack, Lloris punching clear Declan John's free-kick. Townsend raced into the Cardiff half, fed Adebayor drifting out to the left, and the Togo striker laid on the perfect ball for Soldado.
All those goal troubles drifted away as the former Valencia poacher's instincts rushed back, Soldado expertly touching home to hand Spurs a deserved lead.
Former Spurs defender Caulker then wasted a gilt-edged chance to level, the Cardiff captain heading Bellamy's corner against the bar from point-blank range.
Agitated Spurs boss Sherwood screamed at his midfield to stop drifting so deep; no doubt continuing the rant at half-time, with Spurs leading 1-0 but failing to convince.
Cardiff seized the second-half initiative, Bellamy's shot blocked and Dawson rebuffing a Fraizer Campbell cross.
Lennon flew clear in a bid to wrestle control, only for Ben Turner to intervene just as space opened for a shot.
John felled Lennon from behind on Spurs' right flank, on the cusp of the penalty area. Cardiff's left-back was booked but was mightily fortunate not to concede a penalty.
Townsend hit the target from the free-kick, but never really troubled Marshall.
Cardiff sent Kenwyne Jones into action to cause mayhem in the Spurs defence, but the powerful striker could not find a team-mate with his only notable contribution, a knock-down in the box.
Adebayor had the chance to tee up Lennon for a clear scoring chance late on, only to miscue the pass.
Spurs replacement Harry Kane failed to convert a one-on-one with Marshall in the dying stages to boot.