Despite winning the Copa America in July, pressure had been slowly building on head coach Tite following a poor run of results that included defeats to Peru and bitter rivals Argentina – the latter on Friday in Dubai – and draws with Colombia, Senegal and Nigeria.
Brazil took the lead in the ninth minute courtesy of a well-worked goal sparked by Coutinho, whose ball on the overlap to left-back Renan Lodi resulted in a chipped cross from the edge of the area for Paqueta to stoop and head home from five yards.
South Korea captain Son Heung-min tried to drag his side back into the game, initially forcing Liverpool goalkeeper Alisson into a low save with a 22-yard effort in the 15th minute.
Six minutes later, the Tottenham striker then curled a right-footed shot narrowly wide from just inside the left-hand edge of the penalty area.
After Everton striker Richarlison was denied by Jo Hyeon-woo just before the half-hour, the South Korea goalkeeper could then do nothing about Brazil's second in the 36th minute.
Hwang Eui-jo's scything challenge on Fabinho allowed Coutinho to deliver a touch of Samba-style brilliance as he fired a breathtaking 20-yard free-kick into the top-right corner, the 17th goal for his country.
Paulo Bento's side then came within inches of pulling one level before the break when a powerful long-range free-kick from Jung Woo-young took a slight deflection off the wall.
The ball struck Alisson on the chest, forcing a scrambled clearance from Coutinho, whose first attempt with his left foot struck the post, fortuitously rebounding to him for a second effort he hacked away with his right.
After Paqueta headed a yard over from a left-wing Coutinho free-kick in the 55th minute, Brazil made it 3-0 on the hour.
A hopeful low ball through the area from Lodi managed to evade a host of Korean players and fell to Danilo, who unleashed a rocket of a right-footed drive from just outside the area that Jo could only palm into the roof of his net to give the right-back his first goal for his country.
Further chances followed for Richarlison and Manchester City's Gabriel Jesus, before Alisson palmed away two fizzing 25-yarders from Kim Jin-su and Son to leave South Korea without a goal in their last three matches.