The right-back, who featured in every Premier League game as Liverpool were crowned champions last season, received the coveted individual honour after winning a vote of his fellow professionals across the country.
Alexander-Arnold is the first Reds player since Steven Gerrard (2000-01) to claim the accolade and only the fifth since it was introduced, with Ian Rush (1982-83), Robbie Fowler (1994-95 and 1995-96) and Michael Owen (1997-98) the others to have done so.
He emerged as the winner from a shortlist that also included Tammy Abraham, Mason Greenwood, Mason Mount, Marcus Rashford and Bukayo Saka.
“Being a part of the names that I’ve seen on here, and to be a part of such an amazing trophy and be able to receive it, is an unbelievable honour for me and my family. It’s something we’ll always be proud of,” said the 21-year-old upon being presented with the trophy.
“These types of awards, when it’s voted by people who have played against you and can maybe admire or respect the things you do on the pitch, is amazing.
“It’s a big thanks to all those that voted for me and have decided I deserve this trophy. It’s a big thanks to them. It’s huge for me to achieve this and it’s something I’ll never forget.”
Alexander-Arnold scored four goals and provided 13 assists in the top flight as Liverpool surged to the championship with a club-record 99 points.
His tally of assists set a new benchmark for a defender during a single Premier League season, bettering his own record from the previous campaign by one.
The England international had already helped his boyhood club lift the UEFA Super Cup and then a first ever FIFA Club World Cup in 2019 before the domestic title was clinched in the summer.
Alexander-Arnold won the Premier League Young Player of the Season award last month, too, having also been nominated for the top flight’s Player of the Season and PFA Players’ Player of the Year honours.
He was also one of five Reds named in the 2019-20 PFA Premier League Team of the Year on Tuesday evening.
“Obviously first off I’ve got to say thanks to my friends and family, everyone who has helped me achieve this and to get to this point so far,” the Academy graduate added.
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“Without them I wouldn’t be able to be here. They are the ones that see me after we get beat and they’re the ones that help me put those games behind me and keep focused and keep going. I’ve got to give thanks to them.
“Everyone at the Academy for the 10 to 12 years that I was down there, who taught me everything I know really and helped me along the way. I spent the majority of my career and my youth life at the Academy, day in and day out. It’s thanks to those people who moulded me into the person I am today.
“The staff and the manager and the people who have given me the opportunities to achieve things. Without those opportunities nobody can achieve anything, so I’ve got to give thanks to the staff and especially the manager for that.
“And obviously my teammates – without them none of this would be possible. The things we’ve achieved as a team are unbelievable. Hopefully there’ll be many more moments like this.”