González was presented on loan at Real Sociedad on 30 January 2006, until 30 June, alongside Jhon Viáfara, whom the club had loaned from Portsmouth. González said that at Sociedad he would aim to improve his tactical play.
On 5 July 2006, González was granted a work permit, and was allowed to start his Liverpool career, wearing the number 11 shirt. His manager, Rafael Benítez, said, "This is very good news for us and I am absolutely delighted to welcome Mark González to Liverpool as he is a player the supporters will like to see." González made his first appearance as a half-time substitute for fellow debutant Fábio Aurélio in a pre-season friendly away against Crewe Alexandra on 22 July.
González made his competitive debut on 9 August 2006 against Israeli side Maccabi Haifa, coming off the bench in the 85th minute for Steven Gerrard and scoring an 88th-minute winner in Liverpool's Champions League 3rd Round Qualifier to seal a 2–1 win. He scored his first Premier League goal in Liverpool's 3–0 win over Tottenham Hotspur on his first league start for the club on 23 September. He scored just once more for Liverpool, in a 4–0 win over Fulham on 10 December.