Marcus Rashford, Harry Winks, Barkley and Ben Chilwell also started in place of Jadon Sancho, Declan Rice, Mason Mount and Danny Rose.
And it took Rashford just seven minutes to make an impact as he cut in from the left side of the area and drilled home a right-foot shot which somehow evaded goalkeeper Plamen Iliev at his near post.
Soon after Jordan Pickford had to get down smartly to his left to keep out a long-range effort from home skipper Ivelin Popov.
With 20 minutes in the clock England doubled their lead as Sterling exchanged passes with Harry Kane, before crossing from the right to leave Barkley with the easiest of tap-ins from a couple of yards out.
Just past the half-hour mark it was 3-0 to England as Kane fired over an inswinging cross from the right and Barkley arrived to head home from just over six yards out.
Right on half-time Kane was again the provider as he collected a Kieran Trippier pass to cross for Sterling to slide the ball home from close range.
Early in the second half Iliev had to make a block as Kane fired in a fierce shot from distance, before the home keeper blocked a Rashford effort and Sterling put the rebound wide of a gaping goal.
Just before the hour mark Iliev was again to the fore as he denied Sterling and a few minutes later he again rescued his side with a fine save to keep out a Kane effort.
With 69 minutes on the clock England finally got their fifth goal as Kane played in Sterling, who calmly slotted the ball home with his left foot.
Kane should have got on the scoresheet himself with eight minutes to play, but his shot skimmed the outside of the far post with Iliev well beaten.
However, the England skipper made no mistake three minutes later as he beat the last defender before firing a left-foot shot just inside the near post of Iliev to complete the scoring.
Bulgaria 0-6 England
Marcus Rashford, Harry Winks, Barkley and Ben Chilwell also started in place of Jadon Sancho, Declan Rice, Mason Mount and Danny Rose.
And it took Rashford just seven minutes to make an impact as he cut in from the left side of the area and drilled home a right-foot shot which somehow evaded goalkeeper Plamen Iliev at his near post.
Soon after Jordan Pickford had to get down smartly to his left to keep out a long-range effort from home skipper Ivelin Popov.
With 20 minutes in the clock England doubled their lead as Sterling exchanged passes with Harry Kane, before crossing from the right to leave Barkley with the easiest of tap-ins from a couple of yards out.
Just past the half-hour mark it was 3-0 to England as Kane fired over an inswinging cross from the right and Barkley arrived to head home from just over six yards out.
Right on half-time Kane was again the provider as he collected a Kieran Trippier pass to cross for Sterling to slide the ball home from close range.
Early in the second half Iliev had to make a block as Kane fired in a fierce shot from distance, before the home keeper blocked a Rashford effort and Sterling put the rebound wide of a gaping goal.
Just before the hour mark Iliev was again to the fore as he denied Sterling and a few minutes later he again rescued his side with a fine save to keep out a Kane effort.
With 69 minutes on the clock England finally got their fifth goal as Kane played in Sterling, who calmly slotted the ball home with his left foot.
Kane should have got on the scoresheet himself with eight minutes to play, but his shot skimmed the outside of the far post with Iliev well beaten.
However, the England skipper made no mistake three minutes later as he beat the last defender before firing a left-foot shot just inside the near post of Iliev to complete the scoring.