The Danish Brentford captain has made 187 appearances for the west Londoners, scoring 12 goals and registering 16 assists.
“This new contract was a no-brainer for us and Christian,” said head coach Thomas Frank to the clubs’s website.
“Christian has been an integral part of the fantastic journey we have been on these past six years. He is our club captain and one of our most important players.”
“His ability to sense danger and make interceptions is at an extraordinarily high level, as is his ability to play forward on the first or second touch. And he has picked up his goal threat this season!”
“I’m very happy. Hopefully we can continue to be successful together with Christian leading the team.”
Norgaard left Fiorentina to sign for Brentford in May 2019 in a move which reunited him with his former Brøndby head coach Thomas Frank.