Dubnyk was called up by Edmonton early in the 2009–10 season after Oilers starting goaltender Nikolai Khabibulin underwent season-ending back surgery. For the remainder of the season, he served as the team's back-up to Jeff Deslauriers. Dubnyk made his first NHL appearance on November 28, 2009, replacing Deslauriers in a 7–3 loss to the Vancouver Canucks, allowing three goals on 24 shots. He recorded his first career NHL win on March 19, 2010, via a shootout with the Detroit Red Wings; Dubnyk made 31 saves in the win. On March 21, Dubnyk recorded the first regulation win of his career, making 27 saves in a 5–1 victory over the San Jose Sharks.