Late strikes by Luis Suarez and Lionel Messi gave the Catalans an 11-point lead at the top of the table, widening the gap between the two sides.
Atletico began brightly, but their game plan went out of the window when Diego Costa was shown a straight red card in the 28th minute.
It was for a verbal tirade at referee Jesus Gil Manzano.
Atletico produced a gutsy second half display, expertly shackling Barca.
But the Catalans finally found a way past the visitors’ outstanding goalkeeper Jan Oblak with a superb curling shot from Suarez in the 85th minute.
Moments later, Messi sealed victory and quite probably the league title with an irresistibly cool finish into the net.
Barca’s fans jubilantly chanted “champions”, crowing at their surely unassailable lead at the top with seven games remaining.
Atletico realistically needed to win at the Nou Camp for the first time since 2006 to stay in the title race.
They played with ambition and intelligence in the opening stages, keeping the ball for long periods and depriving Barca of space.
But they were rocked by Costa’s moment of madness which killed their early momentum and left them with little choice but to defend for the remaining hour of the game.
Striker Costa reacted angrily to not being awarded a foul after being tackled by Jordi Alba.
He gave a long verbal response to the referee, who to his disbelief pulled out a red card.
Costa had to be shepherded off the pitch by Barca’s Gerard Pique as he struggled to control his temper.
Teammates Diego Godin and Jose Gimenez earned bookings for venting their anger over the decision.
Atletico coped superbly with the setback and numerical disadvantage, controlling the space for the majority of the game.
Messi still carved his way through the middle of the pitch on two occasions, creating openings for Suarez and himself.
But both South American forwards were thwarted by the titanic presence of Oblak.
Atletico naturally had limited opportunities down the other end but were not far from finding a goal when Antoine Griezmann picked out Rodrigo from a free kick.
But the midfielder headed over the bar when Gimenez was standing behind him, in a better position.
Diego Simeone’s side could not last the distance, however, and as their legs inevitably tired, Barca’s attacking quality made the difference.