The former Whitehawk, Macclesfield and Lewes boss takes over following the departure of Jamie Coyle and Adam Flanagan last month.
King, out of work since leaving Welling in the summer having taken the club to the National League South promotion final, will also drive the club’s community development ambitions.
The Darts have endured a difficult start to the season and are 17th - level on points with third-from-bottom Hampton.
The club’s co-chairman Steve Irving thinks the club have got the right man and hopes the club can start climbing the table quickly.
He told the club’s website: “No-one should have any doubt that Steve’s arrival is a statement that the football club we all love, and some of us have served for decades, is determined not to stand still but to grow steadily and surely towards our goal of league football.
“Steve has achieved success at clubs with similar budgets to ours. Today, he has been given, and accepted, the challenge of securing success within the resources we have to reach the level we want to be.
“He gave the board an impressive, credible and deliverable vision to provide not just the success we deserve but also to extend our reputation as a club with strong values and a belief that football can transform lives and communities.
“I would like to add my appreciation to all those fine candidates who applied for the position and especially to the number we invited to meet us.
“The standard of professionalism, enthusiasm and love for the sport that we encountered through many hours of interview was astonishing and it has renewed all of us with a sense that we are part of a game that attracts some of the finest and most decent people in sport.”