Dirty Harry received recognition from the American Film Institute. The film was ranked #41 on 100 Years...100 Thrills, a list of America's most heart-pounding movies. Harry Callahan was selected as the 17th greatest movie hero on 100 Years...100 Heroes & Villains. The movie's famous quote "You've got to ask yourself one question: 'Do I feel lucky?' Well, do ya, punk?" was ranked 51st on 100 Years...100 Movie Quotes. Dirty Harry was also on the ballot for several other AFI's 100 series lists including 100 Years...100 Movies, 100 Years...100 Movies (10th Anniversary Edition), and 100 Years of Film Scores.

The film caused controversy when it was released, sparking debate over issues ranging from police brutality to victims' rights and the nature of law enforcement. Feminists in particular were outraged by the film and at the 44th Academy Awards protested outside the Dorothy Chandler Pavilion, holding up banners which read messages such as "Dirty Harry is a Rotten Pig".

The final scene, in which Callahan throws his badge into the water, is a homage to a similar scene from 1952's High Noon. Eastwood initially did not want to toss the badge, believing it indicated that Callahan was quitting the police department. Siegel argued that tossing the badge was instead Callahan's indication of casting away the inefficiency of the police force's rules and bureaucracy. Although Eastwood was able to convince Siegel not to have Callahan toss the badge, when the scene was filmed, Eastwood changed his mind and went with Siegel's preferred ending.

After Sinatra left the project, the producers started to consider younger actors for the role. Burt Lancaster turned down the lead role because he strongly disagreed with the violent, end-justifies-the-means moral of the story. He believed the role and plot contradicted his belief in collective responsibility for Criminal and social justice and the protection of individual rights. Marlon Brando was considered for the role, but was never formally approached. Both Steve McQueen and Paul Newman turned down the role. McQueen refused to make another "cop movie" after Bullitt (1968). He would also turn down the lead in The French Connection the same year, giving the same reason. Believing the character was too "right-wing" for him, Newman suggested that the film would be a good vehicle for Eastwood.

The screenplay was initially brought to Eastwood’s attention around 1969 by Jennings Lang. Warner Bros offered him the part while still in post-production for his directorial debut film Play Misty for Me. By December 17, 1970, a Warner Brothers studio press release announced that Clint Eastwood would star in as well as produce the film through his company, Malpaso.

The benefit world premiere of Dirty Harry was held at Loews' Market Street Cinema, 1077 Market Street (San Francisco), on December 22, 1971. The film was the fourth-highest-grossing film of 1971, earning an approximate total of $36 million in its U.S. theatrical release, making it a major financial success in comparison with its modest $4 million budget.

The film supposedly inspired a real-life crime, the Faraday School kidnapping. In October 1972, soon after the release of the movie in Australia, two armed men (one of whom coincidentally had the last name 'Eastwood') kidnapped a Teacher and six school children in Victoria. They demanded a $1 million ransom. The state government agreed to pay, but the children managed to escape and the kidnappers were subsequently jailed.

Dirty Harry was a critical and commercial success and set the style for a whole genre of police films. It was followed by four sequels: Magnum Force in 1973, The Enforcer in 1976, Sudden Impact in 1983 (directed by Eastwood himself) and The Dead Pool in 1988.

Warner Home Video owns rights to the Dirty Harry series. The studio first released the film to VHS and Betamax in 1979. Dirty Harry (1971) has been remastered for DVD three times — in 1998, 2001 and 2008. It has been repurposed for several DVD box sets. Dirty Harry made its high-definition debut with the 2008 Blu-ray Disc. The commentator on the 2008 DVD is Clint Eastwood biographer Richard Schickel. The film, along with its sequels, has been released in high definition, on various Digital distribution services, including the iTunes Store.

Although Dirty Harry is arguably Clint Eastwood's signature role, he was not a top contender for the part. The role of Harry Callahan was offered to John Wayne and Frank Sinatra, and later to Robert Mitchum, Steve McQueen, and Burt Lancaster. In his 1980 interview with Playboy, George C. Scott claimed that he was initially offered the role, but the script's violent nature led him to turn it down. When Producer Jennings Lang initially could not find an actor to take the role of Callahan, he sold the film rights to ABC Television. Although ABC wanted to turn it into a television film, the amount of violence in the script was deemed excessive for television, so the rights were sold to Warner Bros.

In September 1981 a case occurred in Germany, under circumstances quite similar to the Barbara Jane Mackle case: A ten-year-old girl, Ursula Hermann, was buried alive in a box fitted with ventilation, lighting and sanitary systems to be held for ransom. The girl suffocated in her prison within 48 hours of her abduction because autumn leaves had clogged up the ventilation duct. Twenty-seven years later, a couple was arrested and tried for kidnapping and murder on circumstantial evidence. According to the Daily Mail, the couple were inspired by the film Dirty Harry, in which Scorpio kidnaps a girl and places her in an underground box. This case was also dealt with in the German TV series Aktenzeichen XY ... ungelöst.

In the 2007 film Zodiac, also set in San Francisco and inspired by the Zodiac Killer, Cartoonist Robert Graysmith approaches police detective Dave Toschi at the cinema, where he is watching Dirty Harry with his wife. When Graysmith tells Toschi he is going to catch the Zodiac killer, Toschi replies, "Pal? They're already making movies about it."

Since its release, the film's critical reputation has grown in stature. Dirty Harry was selected in 2008 by Empire magazine as one of The 500 Greatest Movies of All Time. It was placed similarly on The Best 1000 Movies Ever Made list by The New York Times. In January 2010 Total Film included the film on its list of The 100 Greatest Movies of All Time. TV Guide and Vanity Fair also included the film on their lists of the 50 best movies.

Eastwood was given a number of scripts, but he ultimately reverted to the original as the best vehicle for him. In a 2009 MTV interview, Eastwood said "So I said, 'I'll do it,' but since they had initially talked to me, there had been all these rewrites. I said, 'I'm only interested in the original script'." Looking back on the 1971 Don Siegel film, he remembered "[The rewrites had changed] everything. They had Marine snipers coming on in the end. And I said, 'No. This is losing the point of the whole story, of the guy chasing the killer down. It's becoming an extravaganza that's losing its character.' They said, 'OK, do what you want.' So, we went and made it."

Dirty Harry helped popularize the Smith & Wesson Model 29 revolver, chambered for the powerful .44 Magnum cartridge, and initiated an increase in sales of the handgun. In 2010, Artist James Georgopoulos included the screen-used guns from Dirty Harry in his Guns of Cinema series.

Director John Milius owns one of the actual Model 29s used in principal photography in Dirty Harry and Magnum Force. As of March 2012 it is on loan to the National Firearms Museum in Fairfax, Virginia, and is in the Hollywood Guns display in the william B. Ruger Gallery.

In 2014, Time Out polled several film critics, Directors, actors and stunt actors to list their top action films. Dirty Harry was listed at 78th place in this list.