The Dutch attacking midfielder is Liverpool's second signing of the day and 6th most expensive signing in the club's history.
The deal, worth a total of £25M, puts an end to the four remaining years on his contract at Newcastle and he signs a five year deal at Liverpool.
At 25 years old he should be approaching his best years as an attack minded player.
He will now fly out to the United States where the players are preparing for next week's friendly game against Chelsea.
Speaking after his move was completed Wijnaldum said:
“I’m really excited because Liverpool is a big club with a great history and it’s always a dream to play for as big a club as Liverpool.”
He scored 11 times for Newcastle last season - an ever-present playing in all 38 league games. His best spell came at PSV where he spent the previous four seasons before joining the Geordies and Steve McLaren last summer for £15M.
Newcastle would go on to get relegated to the Championship at the end of the season.
Wijnaldum will be handed the number 5 shirt at Anfield.
Georginio also spoke about fellow countryman Dirk Kuyt's rapport with the fans at Liverpool.
“He deserved it at that time because he worked - he always works hard.
“It doesn’t matter where you put him on the field, he works hard. Supporters appreciate it when you’re trying to work hard for the team and that’s what I have to do also.”
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Jurgen Klopp reacts to the new signing