The 24-year-old completed a £3 million move from Rapid Vienna on Thursday evening to become the club's third signing of the summer.
The former Rapid Vienna left-back is either expected to battle it out with Kieran Tierney or take over the position should the fans' favourite leave this summer.
The Belgian insists it was a no brainer to join the Parkhead club as soon as he got the call from his agent and he can't wait to get out there and show what he can do.
He told Celtic TV: "I found about Celtic's interest last week and they had contact with my agent.
"I said yes, you cannot say no. It was a great opportunity for me to take the next step in my career.
"I just love to play football. I have been dreaming of playing in this big stadium. It was a nice atmosphere in Vienna but here it will be double or treble that.
"I cannot wait to play in this beautiful stadium. It's the same colour but it's a new challenge."