The Reds had a £10m bid for the England right-back rejected, but the 24-year-old has now agreed a five-year deal with the Premier League side.
“I’m delighted and it’s a dream move for me to come here and play for such a big club with all of its history,” Clyne told the club website.
“As soon as Liverpool showed their interest in me, I was happy and just wanted the deal to go through.”
Clyne, who had a year left on his Saints contract, is Liverpool’s sixth signing of the summer.
