The five-time world champions – the only team to appear in every edition of the World Cup – punched their ticket to the finals in Canada, the United States and Mexico thanks to Vinicius Jr.
The Real Madrid star fired Brazil into the lead in Sao Paulo, bundling home from close range in the 44th minute after a cross from new Manchester United signing Matheus Cunha.
Uruguay’s 2-0 victory over Venezuela in Montevideo earlier Tuesday had raised the prospect of qualification for both Brazil and Paraguay at the Corinthians Arena.
Paraguay were left needing only a point to qualify after Venezuela’s defeat, while Brazil knew they could advance with a win.
In the event it was Brazil who seized the opportunity presented by Venezuela’s loss with Vinicius scoring the only goal just before half-time.
A lacklustre Brazil had struggled to create many chances up until that point, with Cunha squandering a golden chance in the 35th minute after heading wide from point-blank range.
But Cunha made up for that miss with a key part in the goal, capitalising on good work from Raphinha to dart into the box and whip in a low cross for Vinicius, who stabbed home the finish.
The win lifts Brazil into third place in the South American standings with 25 points from 16 games, guaranteeing them a top-six finish and an automatic qualifying berth.
The defeat leaves Paraguay with 24 points, meaning they need one point to secure their first World Cup appearance since 2010.
Ecuador can join Brazil by sealing qualification with a point against Peru in Lima later Tuesday.
In other games, Uruguay edged closer to qualification with their win over Venezuela while Chile were eliminated with defeat to Bolivia.
Goals from Rodrigo Aguirre and Giorgian de Arrascaeta secured all three points for Marcelo Bielsa’s Uruguay to leave the two-time world champions firmly on course for a place in next year’s finals.
Like Paraguay, Uruguay need only a point from their final two games to qualify.
Venezuela, who are bidding to qualify for the World Cup for the first time in the nation’s history, are seventh with 18 points from 16 games.
World Cup holders Argentina, who have already qualified, meanwhile came from behind to frustrate Colombia with a 1-1 draw in Buenos Aires.
Liverpool star Luis Diaz fired Colombia into the lead with a superb 24th minute goal, and the Colombians were given a further boost midway through the second half when the world champions were reduced to 10 men after Enzo Fernandez’s dismissal.
But Colombia’s hopes of a vital win were dashed nine minutes from time when Thiago Almada weaved into the box and found the target to level.
The top six finishers in South America qualify automatically for the World Cup, with the seventh-placed team advancing to an intercontinental playoff.
Elsewhere, Bolivia defeated Chile 2-0 to end the former South American champions’ hopes of qualification.
It marks the third straight World Cup that Chile have missed out.
The loss continues a dramatic fall from grace for ‘La Roja’, who won back-to-back Copa Americas in 2015 and 2016. (AFP)