The midfielder scored in the opening minutes of the game as Latics still search for their first win of the 2014/15 season.
Latics got off to the worst possible start, falling behind within four minutes. Paul Gallagher's inswinging free kick was not dealt with in the area and the ball fell for King who fired past Rachubka, giving him no chance.
Only a minute later, the visitors had a superb chance to equalise. Brian Wilson's pinpoint ball into the box found the head of Jonson Clarke-Harris but the striker's header was straight at Jamie Jones in the North End goal.
The game was being played at a high tempo and Preston top goalscorer Joe Garner came close to doubling their early lead on eight minutes but Paul Rachubka held on to the ball well.
Two bookings followed, firstly to Preston's Andy Little for a late challenge on Joseph Mills and captain Liam Kelly went into the referee's notebook after bringing down goalscorer King.
On 15 minutes, George Elokobi unleashed a 30-yard drive that just flashed past Jones' post.
Latics were on top and almost found an equaliser but Clarke-Harris' shot just shaved the wrong side of the post.
As the game started to settle down, both sides seemed content to keep the ball and slow down the pace.
Just before the break, midfielder Carl Winchester broke away in the middle and fed Forte out wide but as the winger crossed, Danny Philliskirk was adjudged to be offside and the chance passed.
Jonathan Forte was presented with a great opportunity straight after the break to find an equaliser for Latics but his free header at the back post sailed wide.
Latics started to dominate possession and were keeping the ball well. Just before the hour mark, a superb cross from left back Mills found the head of Clarke-Harris but the striker could not direct his header on target.
The visitors kept up their pressure and Clarke-Harris opened up his body on 64 minutes and fired a trademark shot at goal but Jones was equal to the effort.
Oldham Athletic were keeping the ball well and showed real creativity but the ball would just not fall.
Clarke-Harris was presented with a free header with just over ten minutes of the game remaining but it was saved by the goalkeeper.
Mike Jones was the next player to unleash a strike from difference but again, the goalkeeper saved comfortably from the midfielder.
With Latics throwing everything forward in a bid to get a winner, they gained a free kick 25 yards from goal with five minutes remaining but Clarke-Harris' effort deflected away from danger.
In the final minute of the game, the ball fell for Forte in the area but the legs of Jones saves the Lilywhites and Morgan-Smith's follow up sailed over the crossbar.
That chance was the last the visitors could muster and they will be disappinted not to come away from Deepdale without a result.
Preston North End: Jones, Laird, Clarke, Wright (Wiseman 84'), Humphrey, Gallagher (Hugill 69'), Garner, Woods, Little, King, Brownhill (Browne 69').
Subs not used: Stuckmann, Kilkenny, Davies, Hayhurst.
Oldham Athletic: Rachubka, Mills (Noble 86'), J.Wilson, Elokobi, B.Wilson, Winchester (Dayton 74'), Jones, Kelly, Forte, Philliskirk (Morgan-Smith 74'), Clarke-Harris.
Subs not used: Coleman, Brown, Dieng, Kusunga.
Goals: Preston North End (King 4') 1-0 Oldham Athletic
Attendance:11,678 (865 visiting supporters)