In a first half of few chances, Oldham's Ryan Flynn had a 20-yard shot turned over the bar by Simon Moore while the home side's best effort came from Mark Duffy whose free-kick was saved by Connor Ripley.
Sharp saw his header deflected wide and Kieron Freeman had a shot blocked.
Soon after the restart, Duffy also had an effort blocked while Sharp tried a first-time shot from inside the area which went over.
Josh Law floated a free-kick just over for the Latics before the hosts took control of the game.
Sharp produced an emphatic finish on 72 minutes after receiving the ball from Duffy on the right-hand side of the area.
Away substitute Freddie Ladapo went close to equalising when his 25-yard volley forced Moore to tip the ball wide.
But Sharp added a second two minutes from time to wrap up the points for the Blades, sweeping home the loose ball after Leon Clarke put Ripley under pressure from Duffy's cross.
Report supplied by the Press Association
Match ends, Sheffield United 2, Oldham Athletic 0.
Second Half ends, Sheffield United 2, Oldham Athletic 0.
Chris Basham (Sheffield United) wins a free kick in the attacking half.
Foul by Josh Law (Oldham Athletic).
Billy Sharp (Sheffield United) wins a free kick in the defensive half.
Foul by Peter Clarke (Oldham Athletic).
Substitution, Sheffield United. Stefan Scougall replaces Mark Duffy.
Attempt missed. Leon Clarke (Sheffield United) right footed shot from the centre of the box is too high.
Corner,  Sheffield United. Conceded by Cameron Dummigan.
Substitution, Sheffield United. Jake Wright replaces Paul Coutts.
Goal!  Sheffield United 2, Oldham Athletic 0. Billy Sharp (Sheffield United) right footed shot from the centre of the box to the bottom left corner. Assisted by Leon Clarke.
Substitution, Oldham Athletic. Carl Winchester replaces Paul Green.
Corner,  Sheffield United. Conceded by Brian Wilson.
Attempt saved. Mark Duffy (Sheffield United) right footed shot from outside the box is saved in the bottom right corner.
Corner,  Sheffield United. Conceded by Brian Wilson.
Substitution, Oldham Athletic. Lee Croft replaces Charles Dunne.
Corner,  Oldham Athletic. Conceded by Simon Moore.
Attempt saved. Freddie Ladapo (Oldham Athletic) right footed shot from the centre of the box is saved in the bottom left corner.
Foul by Billy Sharp (Sheffield United).
Peter Clarke (Oldham Athletic) wins a free kick in the attacking half.
Substitution, Oldham Athletic. Freddie Ladapo replaces Darius Osei.
Goal!  Sheffield United 1, Oldham Athletic 0. Billy Sharp (Sheffield United) right footed shot from the right side of the box to the bottom left corner. Assisted by Mark Duffy.
Corner,  Sheffield United. Conceded by Cameron Dummigan.
Ethan Ebanks-Landell (Sheffield United) is shown the yellow card for a bad foul.
Foul by Ethan Ebanks-Landell (Sheffield United).
Paul Green (Oldham Athletic) wins a free kick in the defensive half.
Attempt missed. Billy Sharp (Sheffield United) right footed shot from the centre of the box is too high.
Attempt missed. Jack O'Connell (Sheffield United) right footed shot from the centre of the box is close, but misses to the left following a set piece situation.
Cameron Dummigan (Oldham Athletic) is shown the yellow card for a bad foul.
Daniel Lafferty (Sheffield United) wins a free kick in the defensive half.
Foul by Cameron Dummigan (Oldham Athletic).
Corner,  Sheffield United. Conceded by Peter Clarke.
Darius Osei (Oldham Athletic) is shown the yellow card for a bad foul.
Chris Basham (Sheffield United) wins a free kick in the attacking half.
Foul by Darius Osei (Oldham Athletic).
Corner,  Oldham Athletic. Conceded by Simon Moore.
Substitution, Sheffield United. Leon Clarke replaces Matt Done.
Delay over. They are ready to continue.
Attempt blocked. John Fleck (Sheffield United) right footed shot from outside the box is blocked.
Second Half begins Sheffield United 0, Oldham Athletic 0.
Two second-half goals from Billy Sharp gave high-flying Sheffield United victory over struggling Oldham Athletic.