The capital-based club emerged champions of the elite division once again, for the 27th time and 13 since the 1997/98 season, when the league was restructured.
Saint George broke the deadlock a minute after recess after a Behaliu Asefa low shot found unmarked Girma, who slotted home from close range.
Four minutes later, winger Ramkel Lok rounded Hawassa keeper Yohannis Bezabeh for the second goal.
Hawassa got a chance to pull one back from the spot after Asecahlew Tamene brought down Medhane Tadesse inside the area. Captain Mulugeta Mihrete made no mistake by halving the deficit in the 83th minute. It was emotional for Mihrete, a former international who bid farewell to the game after years of service.
Saint George finished the season with 55 points, 10 points more than runner-up Ethiopian Coffee. Adama City for the second season running finished in the top three.
Dashen Beer and Hadiya Hossana could not survive the relegation battle, and will play in the second-tier next season.
Saint George’s Ugandan goalie Robert Odongkara was adjudged ‘Goalkeeper of the season’ for the fifth time in a row, after conceding 12 goals all season.
His club-mate Asecahlew Tamene was named ‘Most Valuable Player’ whilst Adama City forward Tafese Tesfaye scooped the top scorer gong after netting 15 goals.
Belay Tadesse went home with ‘Referee of the Year’ prize, with the Fair Play prize going to army team, Defence Force.