The Tigers parted ways with Lee Mansell on Thursday and have acted quickly to source a replacement.
The club are sitting in the lower half of the National League North, Tuesday’s draw at high flying Banbury wasn’t enough to convince the club’s board.
King, who has a great track record of reaching the play-offs, left Dartford in May.
The ex-Macclesfield Town and Welling United boss will be full of belief that Gloucester can reach the top seven despite a challenging first two months of the season.
Chairman Alex Petheram says King’s style of play will leave fans on the edge of their seat.
“I’m delighted that Steven and his coaching team have accepted our offer to join Gloucester City AFC. Steven’s CV is very impressive, he’s a serial winner and plays exciting football,” he said.
“He’s one of, if not the most, successful managers in the National League pyramid.
“We’re delighted he’s chosen Gloucester and we look forward to working with him going forward.”