The 25 year old was part of the Hendon squad which reached the Bostik League Premier Division play-off final last year.
He met his new team mates after today's second pre-season training session.
Manager Steve McKimm said: "He's a good strong, left-sided centre-half. He got player of the season there last year.
"With Hendon going to the other league they've lost a lot of players. With the travelling and his business it didn't work, so we've sorted out a deal for him to come to us."
Lee added: "Steve sold the club to me very well. When I played against Tonbridge it was always a big fan base and it was a no-brainer for me.
"I wanted a different challenge, and I can't wait to get going now."
The first pre-season game is against Whyteleafe on Saturday 7 July.
Updated 16:19 - 11 Jul 2018 by Jim Rowe