The Lewes manager will swap the Dripping Pan for Longmead after Saunders left to take over at Folkestone Invicta.
The club were sold on his exciting, attacking brand of football and he hopes to take his talents to the next level with the Angels in the National League South this summer.
Midfielder Scott Wagstaff will remain in charge until the hand-over in May.
The in-coming manager told the club’s website: “I'm incredibly proud to be joining Tonbridge Angels and stepping into the National League South. This is a fantastic club with real ambition, great sense of community and a passionate fanbase that I cannot wait to connect with.
“After an unforgettable journey with Lewes, I’m excited to start this new chapter and bring the same passion, intensity and belief in ensuring that the football we play represents the values of this proud club.
“Fans can expect a team that plays with identity, is structured, aggressive without the ball, and expressive in possession.
“My focus will be on building a competitive, hardworking, united group that the supporters can connect with and be proud of, whilst providing a platform and environment to support the development of our youth.
“I’m looking forward to working with the players, staff, and everyone connected to the club as we move forward together.”