Harris joined the region in 2014 and has gone on to make 120 appearances for the Men of Gwent.
“I’m excited and happy to sign the contract extension,” said Harris.
“We’re building something at the Dragons and I want to be part of the group that helps the region grow.
“Working under Dean (Ryan) has been good. He didn’t come in and change everything overnight, but with his experience and knowledge we’re making some progress.
“He challenges us as players to learn and our squad is in a good place.”
Harris played for Super Rugby side Stormers and represented Western Province in the Currie Cup before moving to Wales.
The front row ace made his 100th appearance for Dragons when he lined up against ASM Clermont Auvergne in the European Challenge Cup last season.
Director of Dragons Rugby, Ryan, said: “Brok’s performance levels are always consistent which marks him out as a leader.
“He’s a good role model for our younger players and is helping them with their development too.”
Harris follows back row Ollie Griffiths and scrum half Rhodri Williams in signing new terms with Dragons with six of the region’s young academy products having also renewed their contracts earlier this season.
