The Liverpool manager says the German goalkeeper turned down plenty of other interest to move to Anfield.
Liverpool manager Jurgen Klopp has told the club's official website that he was delighted to get a quick deal done for Loris Karius as the goalkeeper had plenty of other interested suitors, and admits he was impressed by the German's desire to join his Liverpool revolution.
Mainz goalkeeper Karius has signed a long-term contract with the Reds for a fee of £4.7 million and will take the number one shirt at Anfield.
It is thought that Klopp has raided his former club with a view to installing the 22-year-old as his first choice goalkeeper ahead of Simon Mignolet next season after the Belgian hit the headlines for a number of unconvincing performances and high-profile mistakes.
Karius was an ever-present in the Bundesliga last season and was voted the third-best stopper in the German top flight in an official fan poll, and was thought to be attracting serious interest from across Europe.
Klopp admitted his delight at being able to secure a quick deal for his compatriot and revealed that he was impressed with the goalkeeper's keenness to become a part of the set-up at Melwood.
The German boss told the club's website: "I am delighted we have signed Loris, he has had a fantastic season with Mainz and has developed into a very good goalkeeper since his return to Germany.
"I am really pleased that we were able to move so quickly to get him and that Loris has shown such a desire to come to Liverpool with a lot of other clubs interested in him.
"I know he will add to the quality we have in this position and I look forward to working with him and all our players when we return for pre-season."
At the age of just 22 Karius already has nearly 100 first-team senior appearances under his belt, and is widely regarded as a goalkeeping star of the future.
The former Manchester City trainee will compete with Mignolet for the number one spot at Anfield as things stand, although speculation suggests that the Belgian may be allowed to leave the club this summer.