Liverpool defender Van Dijk, 27, beat Raheem Sterling, Bernardo Silva, Sergio Aguero, Sadio Mane and Eden Hazard in the vote by his fellow players.
Van Dijk succeeds Liverpool team-mate Mohamed Salah, who won in 2017-18, and is the first defender to take the award since Chelsea centre-back John Terry in 2004-05.
Van Dijk has been one of the key players in Liverpool’s ongoing title challenge this season, playing in every one of their Premier League fixtures.
Signed in January 2018 from Southampton for a world record fee for a defender of £75m, the Netherlands international has been a rock at the heart of the Reds’ defence.
Liverpool have kept 19 clean sheets from their 36 league games this season, 28 of which they have won.
He has also contributed three goals and two assists during the campaign.
“It’s the highest honour you can get as a player to get voted player of the year by the players you play against every week,” said Van Dijk.
“It’s special. I’m very proud and honoured to receive it.”
Van Dijk could still end the season with a Premier League winner’s medal with Liverpool trailing Manchester City by a single point with two matches remaining.