Carlos Queiroz's side had failed to impress during the scoreless draw with Cote d'Ivoire in their opening game of the tournament.
But they were fired into life in the second period against Korea DPR to record the victory that nudges them closer to qualification to the second stage.
Leading through Raul Meireles' 29th minute opening goal, Portugal ran riot after the break with Simao, Tiago (twice), Hugo Almeida, Liedson and Cristiano Ronaldo completing the scoring.
The Portuguese now need a point from their final game with Brazil to ensure they finish second in Group G while the scale of this victory means they have established a major advantage should they lose and the final standings are determined by goal difference.
To cap an impressive afternoon's work for Queiroz's men, Ronaldo's goal was the Real Madrid forward's first competitive international strike in almost two years and will give the player a timely lift ahead of the critical stage of the competition.
Korea DPR had won plenty of admirers for their committed performance in the opening game with Brazil when they narrowly lost 2-1.
And their display during the opening exchanges suggested they had the capacity to make Portugal struggle to get something from this game.
The decisive moment in the game came, however, in the 29th minute when Tiago's superb through ball was collected by Meireles who finished well to put his side in front.
The goal appeared to sap some of the confidence from the Asian side although they battled well to arrive at the break trailing by a solitary goal.
Portugal keeper Eduardo was forced to produce a smart save to deny Jong Tae-Se shortly after the restart but Simao's 53rd minute close-range effort killed off Korean resistance.
Almeida headed the third three minutes later and the game was over as a contest when Tiago slotted home from Ronaldo's cross on the hour.
Portugal refused to ease off and after spurning a number of opportunities, substitute Liedson scored in the 81st minute, followed by a neat individual finish from Ronaldo two minutes from time before Tiago completed the scoring in the final minute.
Portugal(4-5-1): Eduardo; Miguel, Alves, Carvalho, Coentrao; Simao (Duda 75), Mendes, Meireles, Tiago, Ronaldo; Almeida (Liedson 77).
Subs (not used): Beto, Fernandes, Ferreira, Rolando, Pepe, Costa, Danny, Veloso, Ruben Amorim, Deco.
Korea DPR(5-4-1): Ri Myong-Guk; Ri Kwang-Chon, Ji Yun-Nam, Ri Jun-Il, Pak Chol-Jin , Cha Jong-Hyok (Nam Song-Chol 75); Pak Nam-Chol (Kim Kum-Il 58), Hong Yong-Jo, Mun In-Guk (Kim Yong-Jun 58), An Yong-Hak; Jong Tae-Se
Subs (not used): Kim Myong-Gil, Kim Myong-Won, Pak Nam-Chol, Ri Kwang-Hyok, Ri Chol-Myong, Kim Kyong-Il, Pak Sung-Hyok, An Chol-Hyok, Choe Kum-Chol Choe.