The Socceroos star has had to bide his time on the bench since joining La Real from Brighton & Hove Albion in July.
A round of midweek LaLiga games afforded the 29 year-old a chance to make his debut, with regular 'keeper Alex Remiro rested.
There was little Ryan could do to stop Granada's ninth-minute opener, German Sanchez's header taking a heavy deflection on its way in.
Ryan had little else to do for much of the game, as La Real raced to a 3-1 lead on the back of 61 percent possession. His next chance to impress came in the 70th-minute when Luis Milla stepped up to take a penalty after Carlos Bacca was adjudged to have been brought down in the box.
Ryan guessed the right way as the ball sneaked into the bottom right-hand corner.
Real Sociedad held on for the win to move to third in LaLiga standings.