Critical response
Klute was widely praised by critics for its screenplay and Fonda's performance, though some criticized Pakula's unconventional direction. On the review aggregator website Rotten Tomatoes, the film holds an approval rating of 92% based on 48 reviews, with an average rating of 8.2/10. The website's critics consensus reads, "Donald Sutherland is coolly commanding and Jane Fonda a force of nature in Klute, a cuttingly intelligent thriller that generates its most agonizing tension from its stars' repartee." Metacritic, which uses a weighted average, assigned the film a score of 81 out of 100, based on 15 critics, indicating "universal acclaim".
The Los Angeles Times's Charles Champlin praised Fonda and Sutherland's performances, summarizing: "Klute is visually stunning, full of surprises, bewildering and suspenseful, faultless in its timing... Like the best mysteries always, Klute offers more than its diversions and redeems its sordid materials by understanding them and finding them worth pity, not amusement."
Roger Ebert of the Chicago Sun-Times awarded Klute 3.5 stars out of a possible 4, writing that while the thriller elements were poorly executed, the performances of Sutherland and especially Fonda carried the film. He suggested that the film should have been titled Bree after her character, who is the "soul" of the film and avoids the hooker with a heart of gold stereotype: What is it about Jane Fonda that makes her such a fascinating actress to watch? She has a sort of nervous intensity that keeps her so firmly locked into a film character that the character actually seems distracted by things that come up in the movie.
Gene Siskel of the Chicago Tribune was similarly appreciative, writing: "More interesting than the mystery is the character of Bree... the nicest part of her character (due to the script and Miss Fonda's fine performance) is that this prostitute doesn't have a heart of gold. She's a hungup little broad who, when cornered by violence or tenderness, will scratch and bite. Director Alan Pakula's... crisply edited movie runs too long only in drawing out its conclusion….Sharp eyes will solve the mystery midway thru the film. Miss Fonda's performance is superior to her most recent work in They Shoot Horses, Don't They?... Sutherland... presents a controlled posture as the industrious detective. His low profile nicely balances Miss Fonda's incendiary role."
J. Luria, writing for the Professional Psychology: Research and Practice journal, praised the film for its psychological elements, particularly its nuanced depiction of prostitution, noting that "a good mystery plot and excellent acting make this film entertaining. But the sociopsychological scrutiny of the prostitution subculture makes it outstanding. The film unfolds on several levels, the description of the call girl, the struggle for her growth, the relationship of Klute and Bree, and the mystery theme. Overall, it is an excellent blending of the clinical and the literal."
Roger Greenspun of The New York Times, in one of the few negative reviews, wrote, "Pakula, when he is not indulging in subjective camera, strives to give his film the look of structural geometry, but despite the sharp edges and dramatic spaces and cinema presence out of Citizen Kane it all suggests a tepid, rather tasteless mush. The acting in Klute seems semi-improvisatory, and in this Jane Fonda, who is good at confessing, is generally successful. Everybody else merely talks a lot, except for Sutherland, who scarcely talks at all. A normally inventive actor, he is here given precisely the latitude to evoke a romantic figure with all the mysterious intensity of a youthful Calvin Coolidge."
Writing for the Chicago Reader in 1985, critic Dave Kehr declared the film "as close to a classic as anything New Hollywood produced."