Brazil were close to scoring the opening goal of the match in the 60th minute as their left-back Alex Sandro fired outside the area, but he hit the crossbar.
Two minutes later, Brazil broke the deadlock at Lusail Stadium.
Brazilian forward Richarlison finished in the six-yard box following a rebound from Serbian goalkeeper Vanja Milinkovic-Savic.
Then Richarlison scored a spectacular volley after controlling the ball in the area as Brazil doubled the gap in the 73rd minute.
After his second goal, he was subbed out.
In the 81st minute, Brazil could have made it 3-0, but Casemiro hit the bar.
So World Cup record champions Brazil secured a 2-0 win to make a good start to their Qatar 2022 campaign.
The South American powerhouse tops Group G on goal difference.
Earlier Thursday, Switzerland beat Cameroon 1-0 to come second in the group.
Cameroon and Serbia lost their first matches to be in lower ranks.
Only the best two teams in each group will qualify for the last 16 after the third matches.
In the next fixture, Brazil will play against Switzerland on Nov. 28.
On the same day, Cameroon will face Serbia.
Thursday’s results
Group G
Switzerland – Cameroon: 1-0
Brazil – Serbia: 2-0
Group H
Uruguay – South Korea: 0-0
Portugal – Ghana: 3-2
Source: Anadolu Agency