The UKCC level 4 coach said: “I’m excited to be joining a club with Accies’ heritage and, more importantly, their heart and passion for the game.
“It is clear to me that Accies has a structured and positive approach to both the playing side of the game and also the long-term development of its players and infrastructure.
“The club has a great pool of young, talented and committed players to develop and work with and I’m looking forward to getting to know them.”
Leck will join the team at Raeburn Place from Sunday.
He added: “I really enjoyed my time at Hawick.
“The lads and the club were fantastic, however, I needed to earn a living and there are more business opportunities for my kind of work in the city and I reluctantly made the decision to leave The Greens.”