The club parted company with former manager Andy Colley and coach Davie Strathie on Saturday and have moved quickly to bring the ex-Berwick Rangers head coach in.
After a 5-1 defeat at Tynecastle on Saturday, Colley was relieved of his duties after only seven months in charge. The defeat was the Mariners' 11th loss in 15 East of Scotland Football League Premier Division matches this season.
Harvey joins after a spell out of management but brings experience, having managed across the lower divisions.
Starting out at Edinburgh United, he led them to the South Division title in his first season.
At Penicuik Athletic he gained plaudits for an attractive style of football that led the club to the East of Scotland Cup in his second season.
After five seasons in junior football, Harvey was appointed manager of then SPFL club Berwick Rangers but he couldn't steer the club clear of the relegation play-off and was sacked after being leapfrogged by Albion Rovers in the final weeks of the campaign.
In a statement issued today, the club say: “Johnny comes with a wealth of experience in the senior game.
“He had a great playing career at clubs like Bo’ness, Penicuik and Tranent, to name a few.
“Johnny felt it was the right time to get back into management, and after some encouraging conversations, he felt the Mariners were the right move at this time in his career.
“Let’s get behind Johnny and his new coaching staff and give them a warm welcome to Camelon Juniors.”
Harvey will announce his coaching team later this week.
Camelon face Linlithgow Rose away on Saturday in the Challenge Cup.