The 36-year-old, who retired from professional football at the end of last season, was handed the coaching and ambassadorial role in June.
Parker spent two years playing for the North London outfit between 2011 and 2013, featuring in 63 games.
"First and foremost I'm absolutely buzzing to be back," Parker told the club's official website. "I had a couple of good seasons here, enjoyed my time and know a few familiar faces at the club. That's the first port of call.
"I had a good rapport with the fans when I played here and the people at the club and they were keen to get me back in. That was key for me. My role is to coach the Under-18s, there are some good youngsters here and I'm looking forward to it.
"I'm so pleased to see the reaction and I'll get my head down now, work as hard as I can and try to bring some players through."
Parker played more than 550 games across spells at Charlton Athletic, Chelsea, Newcastle United, West Ham United, Spurs and Fulham.