Dikwena have decided to reward Johnson for the good job he and Allan Freese did in the final 11 games of last season, when they led the side away from the relegation zone and up to a 10th-place finish in the League, including a club record five away wins in a row.
Johnson has since been handed the head coach role on a three-year contract, with Freese and Willem Jackson to act as his assistants. The latter will also act as coach for the Under-19 side, while Alex Heredia has been retained as goalkeeper coach.
"We offered Cavin a long-term contract as head coach because we believe that he is the right man to take the club to greater heights," Stars general manager Jason Raine says.
"We subscribe to continuity at Stars, Cavin and his team did a great job in helping us remain in the Premiership. They have laid a solid foundation and we want them to continue where they left off last season.
"Cavin is an experienced coach with an incredible track record in South African soccer at junior and senior level," Raine says.
Stars had received a number of CVs from around the world for the post, but have decided to look internally instead.
The appointment also ends speculation that former Orlando Pirates coach Ruud Krol would be handed the job.