Spaniard Raya made a spectacular save by diving low to his right to deny Mateo Retegui's penalty kick in the 51st minute. He quickly reacted to the follow-up header by leaping across his goal and making a sprawling save to keep his team in the game.
It was a gritty display by Mikel Arteta’s side who soaked up home pressure inside a raucous Stadio di Bergamo and occasionally looked dangerous at the other end.
The closest Arsenal came to scoring was a first-half free kick by Bukayo Saka that was saved well by Atalanta goalkeeper Marco Carnesecchi while Gabriel Martinelli blasted over the crossbar in a rare Arsenal attack after the break.
Arsenal, without injured skipper Martin Odegaard, were not at their best but made sure they returned to London with a point in the bag thanks to the exploits of Raya.
Atalanta were handed the chance to go ahead when Thomas Partey tangled with Ederson on the edge of the area and the referee Clement Turpin pointed to the spot.
After a lengthy VAR check, Retegui eventually took the kick but after a stuttering run, his low shot was read by Raya who then showed elastic-like agility to make the double-save.
“It was a very difficult game but I think we also made it difficult for them, Raya said.
“A point away from home in the first Champions League game, we could have played a bit better but if you can’t win the game then don’t lose it.”
Of his penalty save, he added: “I was lucky to go the right way and unlucky that the rebound fell to him, but I was quick enough to get up and save it. Fantastic to keep a clean sheet.”