Skipper Harry Kane and livewire Raheem Sterling also got on the scoresheet as England's dynamic young side tore Montenegro apart after Michael Keane had brought the visitors level.
Marko Vesovic raised the decibel level in the stadium when he fired the hosts in front against the run of play in the 17th minute, but England were unfazed and went ahead by halftime thanks to Keane's first England goal and Barkley's finish.
Montenegro were still a threat early in the second half and Fatos Beciraj could have equalised, but when Barkley drilled in his second just before the hour the result was a formality.
Kane tapped home the fourth goal after a swift counter-attack from a cut back by Sterling, who slid home from Jordan Henderson's slide-rule pass in the 81st to complete the rout.
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A delighted Barkley said: "It was a great night for myself. Montenegro was always going to be a hard test but we showed character to come back and put in a positive performance."
England, now unbeaten in 32 World Cup and European qualifiers, have scored 10 goals in two games in Group A having thrashed Czech Republic 5-0 with a Sterling hat-trick on Friday.
Manager Gareth Southgate predicted that the trip to Podgorica, where England had drawn on their last two visits, would be a much sterner test than at home to the Czechs.
And he was proved right, despite the final score.
FIRST STARTS
Southgate gave a start to Barkley's Chelsea team mate, 18-year-old forward Callum Hudson-Odoi who became the second youngest England player to begin a competitive international.
West Ham United midfielder Declan Rice, 20, was also handed his first start in place of Liverpool's experienced Henderson.
There was a swagger about England in the opening stages but Montenegro stunned the visitors by taking the lead on their first foray deep into the opposition half.
Vesovic cut inside Keane and, after getting a fortunate run of the ball, sent a diagonal right-footed effort beyond goalkeeper Jordan Pickford and inside the far post.
If Southgate had any fears about how his side would react in a now raucous atmosphere he need not have worried.
Thirteen minutes after falling behind, England were awarded a rather fortuitous free kick on the right and Barkley's curling delivery was met with a thumping header by Keane.
Stefan Mugosa then tested Pickford with a well-struck snap-shot from distance, but it was England who went ahead.
Hudson-Odoi, who was switching wings, showed quick feet to cut in from the left and his shot was directed into the net by the lurking Barkley from close range.
England were sloppy at the start of the second half and Beciraj scuffed wide after a mistake by Danny Rose.
Barkley then fired home in the 59th minute after Montenegro failed to clear and suddenly England were in complete control.
Kane and Sterling, who is in unstoppable form, added the gloss as England scored five goals in consecutive matches for the first time since 1984.
With Bulgaria only drawing 1-1 in Kosovo, England already have a four-point lead in the group.
(Reporting by Martyn Herman; editing by Ken Ferris)
