A fierce strike from Seamus Coleman had given the visitors a 66th-minute lead with a ferocious strike, but they were pegged back when Bryan Oviedo put Dwight Tiendalli's off-target effort into his own net.
But Everton were not to be denied as midfielder Barkley stepped up with six minutes to go to beat Gerhard Tremmel with a strike which nicked the underside of the bar on its way in.
The goal, and another fine individual performance, will ensure the 20-year-old will again be in the headlines after a string of excellent recent displays, and it is hard to see how Roy Hodgson can leave him out of England's World Cup squad.
The win moves Everton up to fourth in the Barclays Premier League table, just two points behind leaders Liverpool.
Swansea remain 11th after another frustrating afternoon which was the epitome of their season to date. There was plenty of good football, but the lack of an end product has cost them points during the first half of the season.
Everton were unbeaten in nine, but Swansea, whose form has been indifferent, made a positive start with Wayne Routledge twice finding space inside the area and slicing wide of goal on the latter occasion.
The Toffees slowly started to settle and Chico Flores almost gifted them an opener when his slack pass was picked off by James McCarthy and moved to Kevin Mirallas.
The Belgian turned Ben Davies inside out, but his shot was well held at the near post by Tremmel.
Ashley Williams then made a crucial block on the winger after a misdirected Jose Canas pass had allowed him to advance on the Swansea box.
There was a pleasing flow about proceedings, although there was little in the way of goalmouth action.
It was summed up when Routledge cut in to find Wilfried Bony, only for the Ivorian to fire over the bar.
Barkley, sporting a skinhead haircut, was the victim of a crunching tackle from the excellent Williams as he looked to get into the box, and the Everton starlet wasted the game's best chance early in the second half.
Passes from Oviedo and Steven Pienaar played the England international in on goal as the Toffees broke, but he stumbled as he was about to pull the trigger.
Williams made a timely challenge to deny a surging run from Coleman as Everton ramped up the pressure, before Barkley produced a trademark driving run to ghost away from Jonathan de Guzman and get away a rising shot that Tremmel tipped onto his bar.
The German's next action was to pick the ball out of his net.
Swansea failed to cut out an Everton throw and the ball was worked right by McCarthy for Coleman to produce a swerving thunderbolt of a strike that beat Tremmel at his near post.
The lead lasted just five minutes. Davies whipped in a cross from the left and Tiendalli got in front of Pienaar to get away a strike which deflected off Ovideo to leave Tim Howard stranded.
Oviedo's intervention meant Swansea had benefited from five own goals in the league this season, a higher tally than any of their own players have managed.
But Barkley made sure it was the visitors who took home the spoils, beating Tremmel with his superb strike to stun the Liberty Stadium.
There was still time for Hernandez and Alejandro Pozuelo to work Howard, but Swansea could not find a leveller.
Source : PA
Source: PA