Ton boss Dan Scorer moved to secure the services of the former Ashford United, Lydd Town and Sevenoaks Town man (pictured, left), following the departure of Ollie Finch.
Scorer said: "I’m excited to have Mark on board as part of the management team. He has a real hunger to step back into football and his motivation to be involved is exactly what I wanted.
"Mark enjoyed a great playing career in Kent - he knows the league and this level well, with great experience that will be put to good use.
"Mark is a real winner. He was a natural leader on the pitch with a real tenacious work ethic, and I think those are great qualities that will really help to continue pushing the players forward."
Of his new club, Wallis added: "I’m really excited to get going. I met with Dan and discussed the club and how he has built the current environment and I was very impressed.
"I’ve been around the Kent Invicta/SCEFL for many years, and the squad Dan has managed to build without a budget is fantastic. They‘re all in it together, which is really hard to find in non-league football.
"I know the majority of the players, having played with many of them before so I know they are great bunch. It’s a different role for me and something I can’t wait to get stuck into.
"I really feel this team will be in the race for promotion this year, and could certainly push for the title, which is something I would love to achieve here.
"With pre-season now upon us, I’m glad I’m now on the coaching side so I can leave the running to the players!"
Welcome Mark!