By SABC Sport
16th June 2023
The 27-year-old will join Albion on a four-year contract on July 1 following the expiry of his deal with the Bundesliga club.
Syria-born Dahoud, who was capped twice by Germany in 2020, becomes the Premier League side's third signing of the summer following deals for Joao Pedro and James Milner.
Seagulls head coach Roberto De Zerbi told his club's website: "I'm excited to have Mahmoud in my team.
"I wanted him when I was at Sassuolo and I'm sure he is going to be a top player for us."
Dahoud began his career with Borussia Monchengladbach before moving to Dortmund in 2017.
He went on to make 141 appearances for this season's Bundesliga runners-up, although his game time was restricted after he had surgery on his shoulder last summer.
Brighton technical director David Weir said: "We're delighted to bring Mahmoud to the club, his quality and ability will really add to the options available to Roberto.
"He's a quality player, he's got lots of experience playing at a high level in Germany with great experience in Europe too."