Johnson first joined the Rocks nine years ago from then-Sydenhams Football League Wessex Premier side Moneyfields.
Has also played for Burgess Hill Town, Worthing and Havant & Waterlooville and spent time on trial at Dagenham & Redbridge and Newport County.
A skilful player who is equally at home on the wing or in midfield, he missed almost all of the last two seasons with a serious knee injury.