Without Neymar and Philippe Coutinho, the Seleccao found it hard to beat the stoic visitors, who maintained their shape throughout and stifled Brazil's normal attacking flow.
The match was heading towards a goalless draw, just like it did between these sides in the Copa America last year, but Firmino tapped home from close range after Yordan Osorio accidentally headed the ball onto the Liverpool striker's path.
The victory maintains Brazil's 100% record in the qualifying rounds. The Selecao also climbed above Argentina to the top of the table with nine points, whereas Venezuela are yet to open their account. Here are the major talking points from the match.
#1 Disappointing performance from Brazil
Brazil were always likely to have the lion's share of the ball here, and sure enough, boasted 74% possession. However, they failed to make the most of it, ending the game with just three shots on target.
It was yet another example of the Selecao struggling to deal with a deep-lying side who were happy to sit back and defend. They cut a swathe through the likes of Bolivia and Peru last month, netting nine times in the process, but Venezuela kept it really tight at the back, not allowing their mighty neighbors too much space to work with.
This might be down to the absence of Neymar, who's often the creative talisman of the side, and also Coutinho, whose incisive runs and crossing ability opens up so many avenues down the right flank. However, the reigning Copa America champions still have enough quality in their side and should've comfortably sailed through this.
With Firmino completely anonymous until the goal, part of the blame must go to the wide men, who offered precious little service to the Liverpool target man. On the other hand, Allan, who's so often the creative mantle of his club sides, came a cropper in his playmaker role.
#2 No VAR controversy this time
Compared to all the chaos that ensued last month due to VAR and it's mismanagement by the referees - Brazil have themselves been witness to this in the game to Peru where the match official made some questionable calls and also took too long to make a decision - today was much better and far less controversial.
It was called into question on three occasions, and every time, the referee was quick to review the incident and make the correct decision. The first two of those were Brazil's disallowed goals in the first-half - Lodi was rightly judged to be offside in the build-up to Richarlison's goal, before Douglas Luiz's effort was chalked off for a nudge on a Venezuelan defender before the shot was taken.
In the second half, the referee checked the pitchside monitor for a potential handball inside Venezuela's penalty area, but quickly concluded there was no foul and restarted the match. Not only were the decisions accurate today, but there was also no time-wasting either, something which upset the flow of many games in the last round.