Meredith, who joined Millwall after five seasons with Bradford City, played the full game but Barrie McKay's first goal for Forest - a long-range effort four minutes before half-time - was enough to secure victory for the home side at the City Ground.
Meredith's international team-mate Jamie Maclaren also made his league debut for his new European club, coming off the bench just after the hour-mark in Darmstadt's 1-1 draw against Brandon Borrello's Kaiserslautern.
There was to be no reunion on the pitch for the former Brisbane Roar team-mates however, with Borrello remaining on the bench throughout.
Former Sydney FC goalkeeper Danny Vukovic played a full game for his Belgian side Genk, conceding twice in his league debut in the 2-1 defeat at Standard Liege.
