The result sent Bournemouth crashing to their seventh home league defeat of the season.
Hughes, who last scored in March 2004 for West Brom against Bradford, struck his first in the 56th minute.
He picked up the ball 30 yards from goal, took a few paces forward before curling around defender Josh Gowling and past the despairing dive of Gareth Stewart and into the top right-hand corner.
Oldham boss John Sheridan must have been delighted after all the criticism he faced when he brought in Hughes back in August.
Hughes repaid his manager's debt big time as he went on to set-up the next goal.
He dinked over a beautiful cross which midfielder Chris Taylor buried into the unguarded net from four yards.
A delighted Hughes finished off a fine afternoon's work with a well-struck penalty three minutes from time.
Bournemouth defender Alex Pearce brought down Taylor with a clumsy challenge and the referee had no hesitation in pointing to the spot.
Hughes stepped up to lash the ball home down the middle of the goal as his delighted team-mates celebrated with him.
Oldham went into the game with only one win in their previous ten, but this always looked like it would be their day as soon as Hughes scored.
Sorry Bournemouth have now not won a home league game stretching back to the March 3.
The Bournemouth supporters let Kevin Bond know exactly what they thought of the performance as they booed the team off at the end.
The Cherries' only real attempt on goal was Max Gradel's turn and shot on the hour mark which was blocked by Mark Crossley in the Oldham goal.