The German tactician says the Egyptian winger absolutely deserves the award after scoring a joint-high 23 Premier League goals and providing the most assists with 13 to claim the playmaker award as well.
This is the second time Salah has won the honour, with his first triumph coming in the 2017/2018 campaign.
The 29-year-old came out on top in a shortlist that included the likes of Harry Kane, Cristiano Ronaldo, Kevin De Bruyne, Sadio Mane and Virgil Van Dijk.
Salah joins the likes of De Bruyne, Ronaldo, Thierry Henry, Gareth Bale, Mark Hughes and Alan Shearer, who have all won the PFA top gong twice.
"What I really love about this prize is that it's voted for by the players," Klopp told Liverpool's website. "That's the one prize that you should be interested in.
"Whatever the supporters say, your own supporters always say, 'Oh you're the greatest' and all the others say, 'How can he win it?'
"So, in Mo's case obviously it's the numbers, scoring goals. But scoring the most goals and having the most assists, with all the ups and downs during a season, all the things I know about football, that's a deserved winner."
Klopp also hailed Salah's commitment to become a better player since joining from AS Roma in the summer of 2017.
"I was incredibly excited about the chance to work together with him. We spoke, yes, that was a very good talk but obviously we all need longer to know about a person," he said of his initial impressions.
"The moment I knew it will be outstanding [was] when I knew him as a person, because he's full of desire, he never will stop developing and he's a workhorse.
"I know we say it a lot but he's really the first in – maybe around Millie [James Milner], maybe Millie beats him from time to time – and he's the last out. So treatment, gym work, all these kinds of things.
"On the pitch, if you tell Mo because of the intensity of the games, 'Mo, you go in now. Thank you very much'. 'I'm good, I'm good, get me another 10 balls.'
"So he deserves it absolutely, and that's why he's the second-time winner of this wonderful trophy. Well deserved, Mo, by the way!"
