Jenkinson played at youth level for Finland throughout his teens, before committing to fighting for a place in Roy Hodgson's squad at senior level last year.
The 21-year-old has insisted that he has no regrets over representing Finland as a youngster, a spell that he feels helped shape a professional attitude to the game.
He told the club's official website: "It was one of the hardest decisions I've ever had to make. I've made so many good friends over the years and I had many successful years representing the Finnish youth teams. I grew as a man and a player playing for Finland.
"I found myself flying on my own to different countries all over the world as a 17-year-old to meet up with the national team, it was an eye-opener. I thoroughly enjoyed it, and have so many great memories.
"I will always have a strong connection with Finland, but ultimately I had to follow my heart. I was born and bred in England, its where I grew up and where I call home. I had to look myself in the mirror and ask myself, 'What do you really feel?'. The answer to that was English, and that was the main reason behind my decision. To this date I only have one cap, and I still have a way to go to break into the squad on a regular basis, but its something I'm working towards."
Jenkinson will return to Finland with the Gunners this weekend, as Arsene Wenger's side face Manchester City in Helsinki.