Former Gillingham midfielder Andrew Crofts has agreed a two-year deal with Brighton.
The 25-year-old was released by the Gills at the end of last season after falling out of favour with manager Mark Stimson.
Crofts is also expecting a battle for a place in Brighton's first XI under manager Russell Slade, who has already signed James Tunnicliffe, Mark Wright and Gary Dicker.
He said: "The manager is still looking to bring in a few new faces.
"He has made some good signings and all the lads here already are good players, so it's tough and good competition."
Slade told Brighton's official website when asked about Crofts: "I've been aware of Andrew for some time.
"He's an international player so that's not bad for a start. He's got good pedigree and was an important player for a good Gillingham team at the time.
"He can sit in for you defensively or he can get forward. He has a good work ethic and I'm pleased to get him."