On review aggregator website Rotten Tomatoes, the film has an approval rating of 73% based on 150 reviews, and an average rating of 6.2/10. The website's critical consensus reads, "Adrift sails smoothly between love story and survival drama, thanks in large part to a gripping central performance from Shailene Woodley." On Metacritic, the film has a weighted average score of 56 out of 100, based on 29 critics, indicating "mixed or average reviews." Audiences polled by CinemaScore gave the film an average grade of "B" on an A+ to F scale.

David Ehrlich of IndieWire gave the film a "B–" and praised Woodley's performance, saying: "When all else fails, which it sometimes does, Woodley is there to right the ship. She's eminently believable as a whip-smart, hyper-capable, iron-willed human being who still finds a way to doubt herself... At its best, she wills Adrift into a moving story about a natural born wanderer who needs an anchor to know her own strength." Variety's Owen Gleiberman also noted the film's flaws while praising Woodley, writing, "For long passages of Adrift, we're pleasantly engrossed without necessarily being riveted. The courtship, heartfelt as it is, has a glorified YA shimmer; the boat-adrift-at-sea sections are like All Is Lost without the ingenuity. But there's a hook, a surprise, a twist that carries you through.