The 22-year-old joined Arsenal last summer for a reported £25 million - a record fee for a Scottish player.
Tierney graduated from the fabled Celtic academy before making his debut during the dying embers of 2014/2015 season, coming on as a late substitute in a league game against Dundee.
During his time in Glasgow, Tierney won three league titles and two Scottish Cup with the Bhoys.
In a QA on Arsenal's official website, the Scot has revealed leaving Celtic was "the hardest decision" of his life but insists the chance to play for the Gunners was another challenge worth trying.
He said: "I would say leaving Celtic was the hardest decision I'd ever had to make and I knew I would always miss Celtic no matter what happens in life.”
"But the chance to play for Arsenal was a challenge that when I heard of it, I was just looking forward to it.”
"I didn't move to Arsenal to live in London. I came to London so I could play for Arsenal.”
"I miss everything about Celtic. And I always will. I am very grateful for every second I spent playing for the club."
Gabriel Martinelli also joined Arsenal last summer from Ituano, a team that plays in Brazil’s third tier.
The 18-year-old has impressed in his first year in Europe, scoring 10 goals in all competitions for the North Londoners so far this season.
Tierney was asked which youth player can be the best in the future, and he was quick to mention Martinelli.
He replied: "I would say Martinelli, I think his hunger and drive and his talent together as one is more than enough to be a world-class player for many years.”
"When I first did a full training session with the team I was put up against Martinelli and the intensity of his play was honestly mind-blowing and I thought to myself: this is the standard I need to be at to play for Arsenal."
