The visitors started better as Yuri Berchiche decided to try his luck from distance early in the first half, but he dragged his shot wide of the post. Inaki Williams, who has scored six goals against Betis, was then sent clean through, but Alvaro Valles came out quickly to stop the goal-bound effort.
The hosts grew into the game, though, as Pablo García actually came closest to scoring before the break, but his strike from the edge of the box was deflected onto the post.
Betis took their momentum into the second half, and Cucho Hernandez in particular was lively, shooting just wide and over with two fierce strikes. However, their efforts would come to waste as Bilbao took the lead against the run of play.
Berchiche whipped a hopeful cross in, and Marc Bartra was the unlucky man to divert it into his own net.
The pendulum swung from then, and it was the visitors who looked most likely to score again in the latter stages.
Substitute Maroan Sannadi tested Valles at his near post, shortly before Aitor Paredes sealed victory, heading home a cross that was flicked on by his opposing defender.
Betis did manage to pull a goal back in stoppage time, as Cedric Bakambu rose highest to head into the far corner, but ultimately it was too little too late. There was also time for Athletic’s substitute goalkeeper, Alex Padilla, to be sent off from the bench in a strange incident, but the visitors held firm regardless.
As a result, Athletic ended a seven-game winless away run in LaLiga against Betis, climbing to second in the table at this early stage, while the hosts fall to eighth, having lost their own unbeaten start.
Flashscore Man of the Match: Yuri Berchiche (Athletic Club)