Gardiner, who stepped down from his post at Dens Park at the end of last month, arrives at Tynecastle as Hearts managing director David Southern prepares to switch to Dundee United as general manager.
Rangers reportedly failed in a bid to lure Gardiner, who was previously a commercial manager at Tottenham, last November.
Hearts owner Ann Budge said: “Scot will take over some of the duties of David Southern, who leaves Hearts at the end of the month to take up his new position of general manager at Dundee United. Scot will work very closely with myself and other members of the board in helping to address the challenges in rebuilding the business.”
Meanwhile, Hearts head coach Robbie Neilson admits the door is still open for Rudi Skacel to return to the club in a coaching capacity. Neilson believes the 34-year-old is the ideal candidate to help develop kids in their youth structure.
Skacel was made the offer earlier this summer and Neilson has not given up hope of bringing the fans’ favourite back.
Neilson said: “There’s no deadline for Rudi. Everyone knows the relationship the club has with Rudi and ultimately it would be good to bring him in, but it’s his decision. The role is still open for him but he’s not got back to us. He would be coming in to do technical work. I think everybody knows his level of technique. His ball mastery is fantastic.
“We think he’d be a great addition as that’s one of the avenues we want to go down, especially with the academy. In the eight to 12 age group you need to hammer home the importance of mastering the ball. It would be good if we can get him in. It’s a big issue that we don’t pay enough attention to that age group. It’s put on the back burner in a lot of places in Britain and that’s the time that you can really develop a player.”