Scotland international Robertson finalised his switch to Merseyside on Friday, penning a long-term contract at Melwood after completing his medical.
The 23-year-old left-back started his professional career with Queen’s Park, and spent three years at the K-COM Stadium after joining Hull from Dundee United in July 2014.
He becomes Jürgen Klopp’s third new recruit of the summer, following the arrivals of Mohamed Salah and Dominic Solanke.