The 20-year-old has put pen to paper on a four-year deal with the Easter Road side and is the club’s first new signing for the 2021/22 season, after goalkeepers Kevin Dabrowski and Matt Macey extended their stays in Edinburgh.
Mackay came up through the youth ranks at the Caley Jags, making his debut at 16, and also spent time on loan at Elgin City.
Speaking to the Hibs website after agreeing his long-term deal, Mackay admitted the style of football at Easter Road had helped make his mind up.
"The way the manager wants to play football is brilliant,” he said. “Having come and seen the facilities, it made me want to come to the club even more.
“It’s a massive club in a massive city, so I’m really looking forward to it.
“Hopefully I can repay the faith the club has shown in me and when the supporters get back they can see the player they’ve signed.
“Hibs are one of the biggest clubs in Scotland and hopefully we can win a few cups and maybe challenge for a league at some point as well.”
He’s been likened to fellow Caley youth product Ryan Christie but Mackay remains focused on improving his own game.
“I’m more of a pacey winger like Martin Boyle, but hopefully I can add something different to the team and a few goals as well,” he added.
‘A really good fit for Hibs’
Head coach Jack Ross was delighted to secure Mackay’s services and is eager to see what the winger can bring to his side.
He added: “I’m really excited because I think it fits with what we’ve been trying to do with the club for the past year, year-and-a-half now in terms of identifying top young Scottish players who will boost the club,” he told the website.
“He’s quick, energetic, scores goals and creates goals so it’s a really good fit for the club.
“We want to have as many players as possible who carry those attributes because that’s how we play.
“I’m delighted we’ve managed to get him here so quickly.”
Mackay will wear number 17 for Hibs.