The Manchester City midfielder provided assists at a remarkable rate last season and has started the new campaign in the same vein, as he laid on two goals at Brussels’ King Baudouin Stadium.
De Bruyne picked out Dries Mertens with an incisive pass for the host’s third goal and later threaded one through the Iceland defence to allow teenager Jeremy Doku to score his first international goal before being substituted in the 81st minute.
It completed an excellent evening for the midfielder, who had earlier been named PFA Player of the Year.
The win puts Belgium two points clear of England at the top of Group A2 after the Three Lions were held to a 0-0 draw against Denmark.
Raheem Sterling played the entire 90 minutes for the second game in succession, but could not inspire a breakthrough on a frustrating evening for Gareth Southgate’s side.
Chances were at a premium in Copenhagen, with Sterling registering England’s first shot on target after 70 minutes with a low drive that Kasper Schmeichel pushed away.
In Group A3, Joao Cancelo and Bernardo Silva both started for Portugal, who beat Sweden 2-0 thanks to Cristiano Ronaldo’s brace.
The Juventus forward’s opener made him the first European to score 100 international goals in men's football, but it was a less positive evening for Bernardo, who limped off after 20 minutes.
Cancelo played the entire game at right-back.