A resistant Eagles side held out for just over an hour before the Tottenham Hotspur man tapped home, and he doubled his tally with a delightful acrobatic effort to seal an opening win for the Selecao, who did not have it all their own way at times.
Serbia were not afraid to stick a foot in during the earliest exchanges as they frustrated a toothless Brazil side, but Vanja Milinkovic-Savic had to be alert in the 14th minute, beating away an inswinging corner from Neymar which may have been heading under the crossbar.
Casemiro then stung the palms of the Serbia number one from long range in the 21st minute, but the five-time champions continued to be quelled by a steadfast red wall and Milinkovic-Savic, who then came out brilliantly to thwart Vinicius Junior in the 27th minute after the Real Madrid man got in behind.
Poor finishing did not help Brazil's cause, as Raphinha found himself one-on-one with Milinkovic-Savic following a slick passing move in the 35th minute, but the Barcelona man could only send a timid effort into the goalkeeper's hands.
Four minutes before the break, a failed clearance from Nikola Milenkovic hit his face before falling into the path of Vinicius Junior, but the Fiorentina centre-back recovered well to put the Brazilian off.
Dragan Stojkovic would have been the much happier of the two managers at the half-time interval, but he would not have been impressed to see a defensive error hand Raphinha a golden chance to open the scoring only 40 seconds after the restart - he hit it straight at Milinkovic-Savic, though.
Only five minutes later, Nemanja Gudelj scythed down Neymar just outside in a very promising free-kick position for the Paris Saint-Germain star, but his effort was deflected behind for a corner, which came to nothing.
Neymar then poked wide from a low Vinicius Junior cross in the 55th minute as Tite's men began to ramp up the pressure, which very nearly paid off on the hour mark.
Left-back Alex Sandro sent a venomous shot towards goal from range, which came back off the post with Milinkovic-Savic beaten, but Brazil would finally get their reward in the 63rd minute.
Some silky footwork from Neymar on the edge of the box presented Vinicius Junior with the chance to send in a curling shot from the left, which Milinkovic-Savic could only parry into the danger area, and Richarlison was there to tap home.
Vinicius Junior should have arguably doubled the Selecao's lead in the 68th minute, but he slipped at the vital moment as the ball sailed high and wide.
However, the Real Madrid starlet would come up with a vital contribution in the 73rd minute, sending in an outside-of-the-boot cross for Richarlison to flick up and fire a spectacular bicycle kick into the bottom corner.
Now well on top, Brazil so nearly made it three when Casemiro's long-range curler cannoned off the crossbar in the 81st minute before Milinkovic-Savic beat away a low effort from Rodrygo just seconds later.
Fred also forced the Serbia number one into a low diving save in the 83rd minute, with the Eagles' resistance now well and truly broken as their mentality turned to damage limitation.
Despite persistent forays forward, Brazil would not make the net ripple again as they stormed to the top of Group G ahead of Monday's clash with Switzerland, while Serbia prepare to tackle Cameroon in four days' time.