The 27-year-old has played 78 matches and taken 108 wickets in all formats since arriving at the 1st Central County Ground for the 2015 season.
Briggs said: “I’m delighted to have signed an extension. We have an exciting squad and are playing some good cricket. Hopefully I can continue to contribute to winning games for Sussex.”
Head coach Jason Gillepsie added: “I’m absolutely delighted that Danny has agreed to re-sign. He’s a very important member of our squad as he’s demonstrated with his performances in all formats this season.
“Danny’s an important cog in the Sussex machine and not just because of his on-field contributions. He’s a great man to have around the dressing room and he’s got a great cricket brain.”