Park ensured the visiting Chilean miners were able to celebrate a home victory on their momentous visit to Old Trafford.
David Beckham was also in a star-studded directors' box to see the Red Devils secure a triumph that maintains their unbeaten record.
Far more importantly, it sends them two points clear of the chasing pack, with a match in hand.
It should have been more. United wasted countless chances, the best of which being a penalty from Wayne Rooney 17 minutes from time that he ballooned over the bar.
For Arsenal, the sorry statistic of a fifth reverse concealed a desperately disappointing performance which did not get that much better even after Arsene Wenger had thrown his star man Cesc Fabregas on in a last desperate bid to secure a share of the spoils.
Ferguson made the point in his programme notes that Arsenal are not the "lilywhites" they are often painted and so it proved during a tight first half in which the Gunners were well prepared to dish out some rough treatment.
On a ground where they have often been ill-treated in the past, the visitors were more than willing to stand toe-to-toe with their opponents, the only surprise being that World Cup final referee Howard Webb did not book Marouane Chamakh and Andrey Arshavin until the last seconds of the opening period.
By that point, the hosts were basking in Park's opener.
The South Korean is one of the men whose recent improvement has retained United's position amongst the title contenders.
It was his injury-time goal that secured victory over Wolves last month and it was an equally well-received effort that allowed United to seize the initiative.
Set free by Rooney's neat nod-down, Nani crossed from the right and not even a deflection off Gael Clichy could prevent the ball bouncing to Park, who contorted his body in such a way as to loop a header over Wojciech Szczesny and into the net.
For Szczesny it was a bitter blow.
Handed his league debut after just three League Cup starts for the Gunners, the Pole had been a confident presence in what has so often been a problem position for Wenger.
Sebastien Squillaci was responsible for the weak clearance that allowed Nani to send a first-time volley whistling past the Pole's right-hand post it was the hand of Chamakh that could easily have brought a penalty for United when he rather awkwardly got in the way of Nani's cross.
Arsenal were a disappointment.
The in-form Samir Nasri was a virtual bystander whilst Arshavin got onto the ball far more often but his final ball was a major let-down.
Twice the hosts came close to doubling their advantage during the opening minutes of the second period.
As part of his impressive evening, Szczesny produced a save reminiscent of Peter Schmeichel in his pomp to deny Anderson, who had burst onto a pass Rooney threaded through the Gunners defence.
Then Nani fired over at the end of a fast counter, started by Anderson robbing Jack Wilshere near the United box and he felt he should have ended it as he screamed in vain for a far-post cross after finding himself completely unmarked.
In between, Nasri had brought a full-length save out of Edwin van der Sar and Nemanja Vidic had blocked as Chamakh tried to turn home the rebound.
Nasri was far more productive, although it was the double introduction of Fabregas and Robin van Persie that really showed how determined Arsenal were not to leave defeated.
The bold move did leave them vulnerable to the counter-attack and it was on one such raid that Nani earned his side a penalty as he checked inside Clichy and forced the Frenchman to handle.
Without a goal in open play since March, the England striker has scored from the spot twice this season. It was also the fifth United penalty in Arsenal's last eight visits to Old Trafford.
There was no goal on this occasion though as Rooney ballooned his effort way over the bar.
It did not sap the striker's confidence and a superb chip brought an excellent save out of Szczesny after latching onto Rio Ferdinand's pass.
Theo Walcott wasted the Gunners' last chance to condemn them to defeat.