Critical reception
Critic Andrew Sarris called the film "a mod masterpiece.” In Playboy magazine, film critic Arthur Knight wrote that Blowup would come to be considered "as important and seminal a film as Citizen Kane, Open City, and Hiroshima, Mon Amour – perhaps even more so". Time magazine called the film a "far-out, uptight and vibrantly exciting picture" that represented a "screeching change of creative direction" for Antonioni; the magazine predicted it would "undoubtedly be by far the most popular movie Antonioni has ever made".
Conversely, Pauline Kael found Blowup to be vague and vacuously symbolic. She argued that these aspects led audiences to find the film artistic and intellectual. In that regard, she likened it to Last Year at Marienbad.
Bosley Crowther, film critic of The New York Times, called it a "fascinating picture", but expressed reservations, describing the "usual Antonioni passages of seemingly endless wanderings" as "redundant and long"; nevertheless, he called Blowup a "stunning picture – beautifully built up with glowing images and color compositions that get us into the feelings of our man and into the characteristics of the mod world in which he dwells". Even director Ingmar Bergman, who generally disliked Antonioni's work, called the film a masterpiece.
Anthony Quinn, writing for The Guardian in 2017 for the film's fiftieth anniversary, described Blowup as "a picture about perception and ambiguity", suggesting an association between elements of the film and the Zapruder film capturing the 1963 assassination of John F. Kennedy.
According to author Thomas Beltzer, the film explores the "inherently alienating" qualities of mass media, where "the camera has turned us into passive voyeurs, programmable for predictable responses, ultimately helpless and even inhumanly dead". Bilge Eberi of Houston Press notes the contrast between "the sinewy movements of the girls, their psychedelic jumpsuits and slinky dresses and multicolored minis", and "the blurred, frozen, inchoate unknowability of the death contained within [Thomas'] image", which "is a glimpse of the eternal and elemental ... that completely reorders, or rather disorders, Thomas's world. As an artist, he can't capture it or understand it or do anything with it. As an individual, he can't possess it or consume it."
Roger Ebert described the film as "a hypnotic conjuring act, in which a character is awakened briefly from a deep sleep of bored alienation and then drifts away again. This is the arc of the film. Not 'Swinging London.' Not existential mystery. Not the parallels between what Hemmings does with his photos and what Antonioni does with Hemmings. But simply the observations that we are happy when we are doing what we do well, and unhappy seeking pleasure elsewhere. I imagine Antonioni was happy when he was making this film."
In his commentary for the DVD edition of the film, Peter Brunette connects it to the existentialist tenet that actions and experiences have no inherent meaning, but are given a meaning within a particular context. According to Brunette, this is demonstrated by the scene in which Thomas takes Jeff Beck's guitar neck out onto the street: "He's rescued the object, this intensely meaningful object. Yet, out of the context, it's just a broken piece of a guitar [...] the important point here being that meaning, and the construction we put on reality, is always a group social function. And it's contextual."
On the review aggregator website Rotten Tomatoes, the film holds an 87% approval rating based on 54 reviews from film critics, with an average rating of 8.3/10. On Metacritic, the film has a weighted average score of 82 out of 100, based on reviews from 15 critics.
American director Martin Scorsese included Blowup on his list of "39 Essential Foreign Films for a Young Filmmaker".
Films such as The Conversation, Deep Red, Blow Out, Jaane Bhi Do Yaaro and Enemy of the State have been inspired by Blowup.