Brown was one of the stand-out performers for Huddersfield last season as David Wagner's side went up through the playoffs in the second tier.
And the Chelsea academy product could make his first appearance for Brighton tonight when they take on Southend in a pre-season friendly.
Internationally he has been capped at every level for England from England U16s to U20s and was part of the squad that won the UEFA European U17 Championships in 2014.
With him having spent the majority of his career since joining Chelsea out on loan a decent season with the Seagulls could be invaluable in helping secure him a spot on the Chelsea team-sheet next year.
Brighton have so far signed goalkeeper Maty Ryan for a club-record fee, along with Markus Suttner and Pacal Gross from German side Ingolstadt.
"He is a player with great potential and will bring a different dimension to our attacking options for the season ahead, alongside our existing strikers".
The 20-year-old versatile forward moved to the Chelsea academy from West Bromwich Albion in the summer of 2013 as an exciting prospect for the future.
Huddersfield were keen to re-sign Brown, but instead he will be playing for Chris Hughton's Brighton.