The centre-back, who has remained Jurgen Klopp’s priority target since the summer and opted to move to Anfield back then as well, will officially join Liverpool on January 1.
Negotiations speedily progressed between the sides after a long process of the Reds repairing the relationship with their counterparts following a tapping-up saga in June that drew a public apology and the Saints refusing to sanction his sale.
With the Netherlands international underperforming at St. Mary's and seemingly going through the motions this season, Mauricio Pellegrino admitted that the club's hardline stance may have not been the wisest action.
"We tried to do the best for the team," he said this week. "The board decided to try to keep our best player at the club. This situation is a big learning curve for everybody and now we decide what is the best for the club."
Van Dijk sat out Southampton's last three matches and a fast resolution suited all parties.
He underwent a medical with Liverpool on Wednesday and beyond becoming the most expensive rearguard purchase in history, also represents their biggest outlay on a player.
Pep Guardiola had been confident of adding the 26-year-old to his high-flying squad when the winter window opened, but he rejected City’s pursuit for a second occasion.
Delighted and honoured to have agreed to become a Liverpool FC player! Today is a proud day for me and my family as I join one of the biggest clubs in world football! I can’t wait to pull on the famous red shirt for the first time in front of the Kop and will give everything I have to try and help this great club achieve something special in the years to come ⚽️ I would also like to take this opportunity to say thank you to Les Reed, the board, manager, players, fans and everyone at Southampton. I will always be indebted to the club for giving me the opportunity to play in the Premier League and despite a difficult last few months I have thoroughly enjoyed my time at Saints and have made friends for life at the club. Thank you for everything Thank you for all the messages of support. I’m now looking forward to meeting my new team-mates and getting started #YNWA
Van Dijk is set to earn £180,000 a week on Merseyside and will wear the No.4 shirt, which he "cannot wait to pull on for the first time."
Klopp's loyalty to the player - he refused to settle on an alternative option in the summer - as well as his long-term vision was enough to convince the Dutch ace that Anfield was still the optimum choice.