Walker, who made 20 appearances between 2004 and 2009 and helped the club win promotion to the Premier League in 2005, will link up with Kevin Keen and work with the club’s U18 team as a goalkeeping consultant until the end of the season.
After retiring in 2013, the 48-year-old has worked in a coaching role for the likes of Peterborough United, Sunderland and Lincoln City.
Most recently, he left his post with Ipswich Town in April 2021.
“It’s great to be back,” Walker told the club’s official website.
“Just doing that drive into Chadwell Heath gain and coming back in has brought back so many memories. It’s great that there are so many people here that were here before as well.
“From the first moment I walked in here as a player, I loved every minute of it. If I can pass any knowledge on to the young goalkeepers and players here then that would be fantastic.”