Yet the former Stromsgodset star says he wishes the Wales international was still plying his trade in Paradise rather than down at the Palace and reckons Ledley played a key part in helping him settle in before his departure for the Premiership.
But Johansen was keen to make the point that he brings different qualities to the pitch than Ledley and is determined to be the best player he can be for the title-winning Hoops.
The 23-year-old said: "I watched Joe Ledley play for Crystal Palace the other night against Liverpool and he had a great game.
"He played a big part in helping me settle in when I first arrived at Celtic in January and I learned a lot from him. Joe is just a fantastic player and I wish he was still here.
"But although we maybe play in the similar position, and his departure gave me the chance to get into the starting team, we are different type of players with different qualities.
"I have not tried to model myself on Joe but concentrate on being the best player that I can be.
"But I definitely learned from Joe and I am grateful to him for that."
With tonight's trip to Scottish Cup finalists St Johnstone, and this weekend's SPFL Premiership finale with Dundee United at Parkhead still to go, the quietly spoken Scandinavian revealed his thoughts are already straying to next season's Champions League qualification campaign.
Johansen said: "I have only played in the Europa League, so the opportunity to play in the Champions League is one that really excites me.
"I know that to meet the challenge of playing in it I will need to improve my game and I am working hard in training on that every day.
"But you can feel the importance the Champions League has to the club from the support and it is a new experience for me that I can't wait to enjoy. Although we have the two league games left, with St Johnstone and Dundee United, it is tough not to be thinking of the Champions League already."
The Norway international added: "But I am really enjoying myself at Celtic, we have already won the league yet still we have a home crowd against Aberdeen of 50,000.
"That just tells you what a massive club Celtic are and how much they mean to the city of Glasgow and to the support."