The Reds announced on Wednesday that they had agreed to sign Van Dijk, 26, from Southampton for £75 million on January 1 - a deal which will make him the most expensive defender of all time.
Puel worked with Van Dijk during their time together at Southampton last season, handing the Dutchman the captain's armband as the club finished eighth in the Premier League and reached the EFL Cup final.
And the Leicester boss is adamant Liverpool have pulled off a big coup by landing Van Dijk, who he believes can establish himself as the best in the world in his position.
Speaking ahead of his side's trip to Liverpool on Saturday, Puel said: “He is one of the best defenders in the world and he has all the qualities to become the best. It is fantastic for Liverpool.
“He can play in different good teams and it is a good reward for him.
“At the beginning of the season it was difficult for him because he wanted to join another club but now he will find his level. I am happy for him, and happy he can't play against us!
“Of course I don't know if it is the right price but for me he is a fantastic player, fantastic defender. I had him for six months and then for the last six months he was injured.
"In those first six months he made progress and developed his play. He has all the qualities.
“He is powerful, has pace and he is comfortable on the ball. He is tall and also has a strong character and personality."