The 24-year-old Greek moved to Anfield on a five-year contract.
Tsimikas, who featured against Wolves in the Europa League last week, will provide much-needed competition for Andy Robertson on Merseyside.
“I’m very happy, I’m very proud to be here. For me, (it is) the biggest club in the world,” he told the club’s website.
– Liverpool FC (Premier League Champions ?) (@LFC) 10 August 2020
“The league here, I really like it. I see it on TV and I’ve dreamed of coming to play in this league since I was a kid.
“(I want) (our) goals. Win the championship and also win the Champions League.”
Tsimikas, crowned three times by his country and known for watching Robertson videos in an effort for his game, becomes Liverpool’s first signing of the summer.
He has played 86 games for Olympiacos in all competitions and has been on loan with Danish club Esbjerg and Dutch team Willem II.
Reds boss Jurgen Klopp said: “He’s a very smart footballer with a winning and competitive attitude, and I like his mindset.
Andrew Robertson now has an assistant on the left side (Adam Davy/PA)
This fits perfectly with the environment and preference we already have in our dressing room.
“He has showed already at a young age he can experience football in a different country and do well – and he has been a big part of the success Olympiacos has had to win their title this season and in their European campaigns.”
Nice and Napoli were to sign Tsimikas, but Liverpool had established a long-term relationship with their agent, as early as August 2018, when he played in a Europa League qualifying match at Burnley, and in January 2020 he was known as a viable left-back. . Option.
Leicester and Seville, among other clubs, tried to join the race when Liverpool’s interest became public, but the player had already committed to the Reds.