England coach Fabio Capello has said that it was important for his side to win against Bulgaria, but admitted that there is still room for improvement.
The Three Lions took the lead in Sofia after 10 minutes through Gary Cahill, before Wayne Rooney added two more to make it 3-0.
England are now three points clear at the top of their Euro 2012 qualifying group after Wales beat joint-leaders Montenegro in Cardiff.
"It was important to win here," the England boss told Sky Sports News. "We played a really good game. It was not easy here. We scored three goals. We prepared really well.
"At some moments we pressed a lot and won back the ball, at other moments we didn't press and go forward for the last 10 minutes of the first half. But I'm happy, for the result but also for the spirit of the team.
"We've got players with a lot of quality. They are very good technically, but I think we can improve."
England continue their qualifying campaign on Tuesday against Wales at Wembley.
