Having lost 1-0 to Slovakia in their Group E opener, collecting three points was imperative to boost their chances of reaching the knockout stage.
The City pair started the clash for their nation and they recorded a precious victory thanks to goals from Youri Tielemans and De Bruyne either side of half-time.
It means Domenico Tedesco’s team are currently on three points and know a draw with Ukraine, their final first phase match, will likely seal progression whereas a win would guarantee a place in the last-16.
Belgium made the perfect start when Doku advanced with the ball, played it into Romelu Lukaku who teed up Tielemans who unleashed a vicious drive into the bottom corner from the edge of the box.
Undeterred from conceding early, Romania were denied an equaliser soon after when Radu Dragusin’s header from close range was stunningly saved by Koen Casteels.
It didn’t take long for De Bruyne to work his magic when he danced his way through midfield and switched the ball to Dodi Lukebakio who cut onto his left and whipped a venomous effort towards goal which was saved well.
Belgium continued to press before half-time and it was De Bruyne who came close on the cusp of the interval when he drove to the edge of the box but under-hit his effort into Florin Nita’s gloves.
Shortly after the break, Romania fired a warning shot at the Red Devils when Dennis Man stung the palms of Casteels with an speculative effort from range.
And the second half continued at an electric pace with De Bruyne coming close to extending his nation’s lead when he curled an effort just wide of the post from the edge of the area.
Belgium thought they had finally doubled their lead on 64 minutes when Lukaku latched onto a pass from City’s classy midfielder and coolly slotted home - but after a VAR review - the Chelsea striker’s effort was ruled out for offside.
The end-to-end affair continued and Man squandered a great chance when he burst into the box but saw his shot blocked from close range by Casteels.
But the game’s second goal fell to Tedesco’s side when De Bruyne bravely battled for the ball inside the box and poked home to seal three points.
Belgium conclude Group F against Ukraine on Wednesday 26 June at 17:00 (UK).
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