Commercially and critically successful on release, it earned more than six times its budget and won three Academy Awards including Best Actor for Gregory Peck and Best Adapted Screenplay and it was nominated for eight, including Best Picture, Best Director and Best Music Score.

Critics of the film on release praised its story, script, performances and music with Bosley Crowther of The New York Times stating that “Mr. Peck and little Miss Badham and Master Alford… portray delightful characters” and that “their charming enactments of a father and his children in that close relationship, which can occur at only one brief period, are worth all the footage of the film”.

Walt Disney praised the film stating “That was one hell of a picture. That’s the kind of film I wish I could make.”

Roger Ebert was more critical of the film and such criticism is true to many viewers today, with his critique observing that the film is centred more on Atticus serving as the white man standing for a helpless black man - an example of the cinematic white saviour trope – while it also is a product of “the liberal pieties of a more innocent time, the early 1960s, and it goes very easy on the realities of small-town Alabama in the 1930s.”

American Film Institute ranked the film at #25 in their 2007 ranking of Greatest American Movies of All Time, the #1 Best Film in the Courtroom Drama genre and voted Atticus Finch as The Greatest Movie Hero of the 20th Century in 2003, while the British Film Institute included it in their 2020 list of The 50 Films You Should See By The Age of 15.

Today it is positively reviewed at 93% on Rotten Tomatoes and 88 out of 100 on Metacritic, with critical consensus stating “To Kill A Mockingbird is a textbook example of a message movie done right – sober-minded and earnest, but never letting its social conscience get in the way of gripping drama”.