Gardiner started his new role on Monday, with his new side set to face his former club at Hampden on Saturday in the William Hill Scottish Cup semi-final.
He worked for the Jambos between July 2014 and August 2017, and was involved in several high-profile projects with Hearts, including the building of the new main stand at Tynecastle Park.
He has also held positions at Dundee, Tottenham Hotspur and Rangers.
Gardiner said following his appointment: “I like what I have seen on the park in terms of the style of football being encouraged by the manager and the hard work of the board of directors to create a more sustainable business model. “Their commitment to promoting a youth development system is also highly commendable.
“I am also fully aware of the challenges facing the club in terms of reduced income from playing in the Championship for a second season.
“That said, the numerous meetings and phone calls I have had with the various board members over the last couple of weeks have convinced me that we can make a positive impact on the football club, both on and off the pitch.”
Gardiner said he would be focusing on creating a “strong support team” to bring in the financial clout needed to “field a side capable of progressing to the Premiership”.
He added: “There is no doubt that a successful football side in Inverness is good for the city.”
Graham Rae, club chairman, welcomed the appointment, and said: “Scot has attended a number of our games this season and I have always been impressed with his knowledge of the game, both on and off the park.
“He has a wealth of experience in the football and business world and is highly regarded in the game.”