Alexis Mac Allister joins Liverpool after his club Brighton & Hove Albion reached an agreement to sell the player in an undisclosed fee.
Both clubs had confirmed the move of the 24-year-old through their different media platforms.
Liverpool wrote on its website that the 24-year-old has successfully completed a medical and agreed personal terms to become the Reds' first signing of the summer window.
Reds added that Mac Allister will arrive at Anfield less than six months on from helping Argentina win the World Cup in Qatar last December,capping a highly impressive season with Brighton.
According to Liverpool,the midfielder told Liverpoolfc.com:"It feels amazing.It's a dream come true,it's amazing to be here and I can't wait to get started.
"I wanted to be in[from] the first day of pre-season,so it's good that everything is done.I'm looking forward to meeting my teammates.
"It was a fantastic year for me-World Cup,what we achieved with Brighton-but now it's time to think about Liverpool and try to be a better player and a better human being every day."
He arrived in UK few years ago in 2019 where he played for Brighton for three-and-a-half successful seasons,in his country he was playing for Argentinos Juniors and played for Boca Juniors.
His first debut on the English Premier League was on March 2020 and during his stay at Brighton made a total of 112 appearances ,and 98 of those appearances were in the EPL.
He will become a seventh Argentinian to wear the Liverpool jersey in the club's history.
The signing of Mac Allister seems to be huge excitement for the Liverpool manager Jurgen Klopp because he will be able strengthen his squad.
According to club's website,upon completion of the deal,Klopp told Liverpoolfc.com:"We are adding a very talented,very smart,very technically skilled boy to our squad and this is super news,really it is.
"I do not think the football world needs me to say too much about Alexis' qualities because they are already pretty well known but it is clear that he is someone who can play in a number of positions in the midfield and is an all-rounder,I would say.He is calm and composed and someone with proper game intelligence."
Mac Allister managed to score 20 goals in overall during his stint at Brighton and that attracted more clubs to chase his signature because it is rare to find a midfielder of his calibre when he faces the goalpost.
He will wear jersey number 10 in the upcoming season and would share the training field with the likes Mohammed Salah and many others as Reds has cream of the crop players.