The woman accused him of various acts of aggression and violence. Police initially brought four charges against the 32-year-old, who was arrested at a city hotel just hours before Sri Lankan team was due to fly out home on November 6.
Prosecutors later dropped three of those charges.
Gunathilaka maintained his innocence, pleading not guilty to one count of sexual intercourse without consent.
During the judge-alone trial, defence lawyers attacked the credibility of the woman, claiming her story shifted over time and that she edited her version of events to paint Gunathilaka as an aggressive person.
Gunathilaka had been on bail during the trial but was unable to play international cricket or return to his hometown of Colombo in Sri Lanka.
He travelled to Australia with Sri Lanka’s Twenty20 World Cup squad last year but only played in the team’s first game before being ruled out of the tournament with a hamstring injury.