LuaLua settled the first match of the English second tier season when he netted from wide on the left side of the Forest penalty area five minutes into the second half at the Amex Stadium.
The 24-year-old's winner stopped Brighton's run of three successive losses in their opening match of the season.
It was an encouraging start for Chris Hughton's team, who narrowly avoided relegation to League One last season and featured debutants Tomer Hemed, an Israel forward, and Cameroon left-back Gaetan Bong.
Seagulls legend Bobby Zamora, who re-signed for the club this week, wasn't fit enough to feature, but the former Tottenham and West Ham striker received a warm welcome from the 24,623 crowd when he strolled onto the pitch before kick-off.
Defeat was tough on Forest, who have been hit by Financial Fairplay transfer restrictions and injuries during pre-season.
Britt Assombalonga and Matt Fryatt, the club's leading strikers, were both sidelined, but Dougie Freedman's side hit the woodwork early on through Henri Lansbury's free-kick.
Forest midfielder Michail Antonio's rasping shot was pushed away by goalkeeper David Stockdale as the visitors battled for an equaliser that wouldn't come.