The wonderkid debuted at Anderlecht at just 16, and is widely considered one of the brightest prospects in the game.
Both Monaco and Arsenal showed interest in him this summer, but he decided on last season's Champions League semi-finalists as they rebuild following some key departures.
According to Tielemans, the chance to shine in Ligue 1 was too good to turn down, regardless of overtures from Arsene Wenger's side.
“Monaco was just the best step for me. I knew that I could secure a place in the midfield because the vice-president had entrusted me with what he was planning," the 20-year-old told Het Laatste Nieuws.
"Some outgoing moves were certain, but I couldn’t say that at the time.
“I also wanted to start my preparation with my new team, so that I had time to adjust and prove myself to the coach. At the end of the Belgian league play-offs I was doing something about it - thanks to our big lead, it was almost certain that we would be champions. And by making a quick choice, before travelling with the national team, I could go without worrying about my future."
Tielemans acknowledged talks were held with Arsenal, but maintained he was not prepared to sit on the bench at a critical time in his development.
“Could I have gone to the Premier League? Yes, but Monaco was the first and most concrete team.
“I knew there was not much going on with Arsenal’s interest. The board wanted to keep the players they had together to finish higher in the Premier League. You must also be honest. When you see the midfielders that are playing at Arsenal... those are top footballers. I knew I would not get a lot of playing opportunities there. That's why I didn't think about it anymore.
“I've never said no to a club. What I did do was immediately make clear where I wanted to go."