The Scotland international becomes Liverpools third major signing of the summer following the arrivals of Dominic Solanke and Mohamed Salah
The Scotland international has signed a long-term deal at Anfield having completed a medical on Thursday, with his fee set to rise to as much as £10m should he meet certain criteria during his time on Merseyside.
Robertson’s arrival could allow James Milner to move back to a more familiar role in midfield after he filled in admirably at left-back for much of last season, while Alberto Moreno and Jon Flanagan remain in Jurgen Klopp’s squad.
Robertson has played 57 Premier League matches for Hull, scoring one goal and laying giving four assists, and was one of the Tigers’s most consistent performers as they were relegated in 2016-17.
“It feels a wee bit surreal just now. Obviously I’m delighted,” he told Liverpool’s website upon his signing. “There’s been a lot of speculation over the last couple of weeks but I’m glad that the deal’s finally been done and I’m a Liverpool player.
“My family are proud of what I’ve achieved so far and they’re all over the moon with the move, as well as me of course. We’re all just looking forward to being part of the Liverpool family now.