The 33-year-old has finalised a deal with reported wages of up to £700,000-a-week.
Liverpool captain Jordan Henderson has signed for Saudi Pro League side Al-Ettifaq.
The announcement was made by both clubs announced on Thursday.
The England midfielder is the latest big-name player to move from the Premier League to Saudi Arabia after 12 years at Anfield.
“We can confirm @JHenderson has completed a transfer to Al-Ettifaq,” Liverpool said on their social media channels.
Al-Ettifaq posted: “A leader. A warrior. We’re simply thrilled to have him.”
The 33-year-old has finalised a deal with reported wages of up to £700,000-a-week.
Liverpool are due to receive an initial £12 million ($15.5 million) from the Saudi club.
“As his Anfield chapter now comes to a close, everyone at the club wishes to place on record their thanks and gratitude for everything Jordan did for us during his 12 years as a Red,” Liverpool said in a statement.
Henderson said his goodbyes to the club’s fans on Wednesday.
“It’s hard to put these last 12 years into words and it’s even harder to say goodbye,” he said in an Instagram post. “I will always be a Red. Until the day I die.
“Thank you for everything. You’ll never walk alone.”
Henderson led the Reds to their first English league title for 30 years in 2020, a year after lifting the Champions League.
The England international will be reunited with former Liverpool team-mate Steven Gerrard, who is Al-Ettifaq manager.
Henderson joined Liverpool from Sunderland in 2011 and succeeded Gerrard as skipper at Anfield in 2015.
France striker Karim Benzema quit Real Madrid to join Al-Ittihad, following his former Real team-mate Cristiano Ronaldo, who plays for Al-Nassr.
Other Premier League players who have moved to Saudi Arabia include Chelsea’s N’Golo Kante and Liverpool forward Roberto Firmino.
Henderson’s move has attracted criticism due to his long-time support of LGBT+ issues.
Saudi Arabia’s lavish spending on sport is often criticised as “sportswashing” — an attempt to shift the focus from its record on human rights.
The conservative monarchy executed 81 people in a single day last year, outlaws homosexuality and triggered international condemnation when journalist Jamal Khashoggi was murdered in the Saudi consulate in Istanbul in 2018.