Gorka Pintado fired his first goal of the season to send the Swans up to fourth spot in the Championship.
El Toro connected with Nathan Dyer's right-sided cross to fire past Chris Weale just after the half-hour mark to end his scoring drought which stretched back 10 months.
The Swans enjoyed good periods of possession during the first-half but goalkeeper Weale was rarely tested, while Leicester showed their strength in the second period as they went seeking a leveller.
It never came and the Swans held on to record their first win of 2010 and move up two places in the standings.
Four players returned to Swansea's starting line-up after missing the last outing against the Foxes two weeks earlier.
Two changes came at full-back where Angel Rangel and Fede Bessone returned, in place of Albert Serran and Marcos Painter, while two alterations also came in midfield.
Leon Britton replaced Jordi Lopez in front of the back four and Nathan Dyer came in for the injured Cedric van der Gun.
Swans: Dorus de Vries; Angel Rangel, Garry Monk(C), Alan Tate, Fede Bessone (Ashley Williams, 78'); Leon Britton, Joe Allen (Albert Serran, 73'), Darren Pratley, Nathan Dyer, David Cotterill; Gorka Pintado (Craig Beattie, 78').
Not Used: David Cornell (GK), Lee Trundle, Mark Gower, Tom Butler.
Leicester City: Chris Weale, Michael Morrison, Wayne Brown, Jack Hobbs, Ryan McGivern, Yann Kermorgant (Martyn Waghorn, 60'), Matt Oakley (C), Andy King, Lloyd Dyer (Dany N'Guessan, 71'), Matty Fryatt (Steve Howard, 60'), Paul Gallagher.
Not Used: Conrad Logan (GK), Robbie Neilson, Richie Wellens, Chris Powell.
Attendance: 15,037 Away: 930
The clouds hovering above the Liberty Stadium were grey in colour and the rain started lashing down as the referee got this contest underway.
Leicester were lining-up for the first time at Swansea's 'new' home and straight from the kick-off, taken by the Foxes, they lost out on possession to Gorka Pintado.
The home side enjoyed spells with the ball during the opening minutes with the midfield pressing the visitors' defence, while down at the other end Alan Tate outmuscled Matty Fryatt on the six-yard box.
Fryatt had the first proper chance of the aftermoon with 10 minutes played when he connected with Paul Gallagher's cross, only to send his effort over from a matter of yards, while movement shifted straight up to Leicester's area where Pintado's effort was deflected wide by Jack Hobbs.
Skipper Garry Monk met David Cotterill's resulting corner with his head but was easily cleared, while two shots from distance shortly after the quarter-hour mark from Fede Bessone and Darren Pratley caused Chris Weale no problems between the Leicester sticks.
Michael Morrison was booked for a challenge on Nathan Dyer barely a minute after the tricky winger raced down the line after playing the ball between his legs, and he got the better of the ex-Cambridge youngster again moments later, cutting past him inside but, in the end, pulled a weak shot wide of goal.
The Swans continued to play their passing game and enjoy spells of possession but were up against a strong and stubborn Foxes defence, resulting in the third long-range effort from the hosts - Cotterill this time attempting a similar effort to that in the FA Cup tie, but this time was off target.
Joe Allen connected with a Nathan Dyer cross to send the ball over from close-range after the half-hour, but the winger enjoyed better luck with his delivery moments later.
Pratley fed the ex-Saint down the left to get the better of full-back Ryan McGivern, reaching the ball before it went out of play to cross low into the box where Gorka Pintado was placed at the near post to fire home his first goal of the season, and first for 10 months.
The momentum was with Paulo's side at this stage and Pratley almost grabbed a second with 42 minutes on the clock, capitalising on Morrison's slip to cut in from the right but curl a low strike past Weale and around the far post.
Half-Time: Swans 1 Leicester 0
Despite enjoying longer spells with the ball in the first-half it was Leicester that looked more dangerous at the start of the second period.
The Foxes were applying the pressure inside the first 10 minutes and had a claim for a penalty turned down as Matty Fryatt's strike deflected off Alan Tate for a corner.
Yann Kermorgant mis-hit his effort from the eventual delivery before the home side started to re-stamp their mark.
Nathan Dyer was looking dangerous as he switched between both flanks and he was a matter of yards offside when he was played through on goal by Darren Pratley.
His partner in crime, David Cotterill, saw a pin point delivery miss the head of Pintado by inches before the two linked-up again just before the hour when the goalscorer did meet his right-sided delivery but failed to connect properly, seeing the ball land in the safe hands of Chris Weale.
But an error by Darren Pratley almost gifted Leicester an equaliser on 64 minutes when he played the ball directly into the path of substitute Steve Howard, he laid off Lloyd Dyer but his low strike, fortunately, fell the wrong side of the post.
And they were handed a glorious chance 16 minutes from time - Paul Gallagher carried the ball past Fede Bessone and across the box to the feet of old foe Dany N'Guessan, the player who has broken Swansea hearts twice already this season, but, with the goal gaping in front of him, all he could do was play straight into the hands of Dorus de Vries who was still on the floor.
Craig Beattie was introduced with just over 10 minutes to go to play in his first game since early December and he used his strength to put himself about in attack.
And while the likes of Dyer and Cotterill continued to get themselves into dangerous positions there was no threat on Chris Weale's goal.
Steve Howard drove a shot high over de Vries' goal while the Dutchman was called into action with less than a minute of normal time to play by pushing Jack Hobb's cross-come-shot over the top from underneath his crossbar.
The Swans were then forced to play the four minutes of added time with 10 men after substitute Albert Serran limped off clutching his knee, but they held on to record their first win of 2010 to leapfrog the Foxes into fourth spot.