The win came after an impressive 4-2 start against Argentina, and Malaysia now have full points after two matches going onto the rest day of the tournament.
Malaysian Hockey Confederation (MHC) president Tengku Abdullah Sultan Ahmad Shah walked onto the pitch after the win and gave a pep talk to the players.
"I am impressed with your performance today, and there are only minor adjustments that need to be made like more swifter counter attacks, and also don't waste too many opportunities in the semi-circle.
"You guys are the Asian champions (Junior Asia Cup title holders) and now we must win this tournament to show our strength going into the Junior World Cup."
Skipper Fitri Saari led by example when he opened accounts with a deft hit in the 13th minute to give Malaysia the lead.
And cheered on by fans with drums and constant singing, Malaysia mounted a series of attacks to increase their lead.
But the second goal never came, as Malaysia kept missing in the semi-circle, and even bungled their only penalty corner in the 25th minute.
The one-goal lead did not look impressive, as the players trooped into the dressing room to receive instructions from their coach K. Dharmaraj.
And it was a dream re-start as Malaysian won their second penalty corner a minute into the match, and Shahril Saabah made it 2-0 by scoring his fourth goal of the tournament in the 37th minute.
Malaysia mounted a series of attacks after that goal, and increased the lead off their seventh penalty corner in the 48th minute.
This time, it was the turn of Zulhairi Hashim to flick in the third goal, and the Koreans looked like they were heading for a drubbing.
And the fourth goal came off a lovely combination when Shahril beat two Koreans and made a pass to Syamim Yusof to slam home in the 64th minute.
The Koreans' consolation goal was scored in the 67th minute off a field attempt by Seo in Woo.
But Rashid Baharom struck in the 69th minute with an attempt from an acute angle and Malaysia triumphed 5-1.
Pakistan came back from a goal down to hammer England 6-2 to strengthen their quest of playing in the final. The thumping win came at the back of a 3-0 drubbing of South Korea on Sunday.
The Pakistani goals were scored by Muhammad Tousiq (11th, 20th), Muhammad Umair (35th, 69th), Ayub Ali (54th) and Muhammad Suleman (62nd).
Richard Gall (fifth minute) and Luke Taylor (15th) scored for England.
In another match, India came back from the dead to edge Argentina 3-2. The match belonged to Argentina until the 60th minute when they were leading 2-1, but team manager Orozco German then started abusing the umpires and was removed from the bench.
The Argentine players looked rattled by the incident, letting in two goals in two minutes to hand the three points to India.
India's goals were scored by Affan Yousuf (23rd) and Ramandeep Singh (60th, 62nd). Both the Argentina goals were scored by Carlos Ibarra in the 16th and 42nd minutes.
FIXTURES --Today: Rest Day.
Sept 26: England v Argentina (4pm), South Korea v India (6pm), Malaysia v Pakistan (8pm).
Sept 28: Argentina v Pakistan (4pm), India v Malaysia (6pm), South Korea v England (8pm).
Sept 30: Final and placing matches.