Omni Consumer Products (OCP), on the verge of bankruptcy, creates an armed force called the Urban Rehabilitators ("Rehabs" for short), under the command of Paul McDaggett (John Castle). Ostensibly its purpose is to combat rising crime in Old Detroit, augmenting the ranks of the Detroit Police in apprehending violent criminals. In reality it has been set up to forcibly relocate the residents of Cadillac Heights, killing some of them (including the parents of Nikko, a Japanese-American computer whiz kid) in the process. The Police force is gradually superseded by the Rehabs, and violent crime begins to spiral out of control. The Delta City dream of the former OCP CEO, "Old Man", lives on with the help of the Japanese zaibatsu Kanemitsu Corporation, which has bought a controlling stake in the organisation. Kanemitsu (Mako) sees the potential in the citywide redevelopment, and moves forward with the plans to remove the current citizens. The company develops and uses its own ninja robots (called "Otomo") to help McDaggett and the OCP President (Rip Torn) overcome the resistance of the anti-OCP militia forces.

When RoboCop (Burke) and partner Anne Lewis (Allen) try to defend civilians from the Rehabs one night, Lewis is mortally wounded by McDaggett and eventually dies. Unable to fight back because of his 'Fourth Directive' programming, RoboCop is saved by members of a resistance and eventually joins them. Due to severe damage sustained in the shoot-out RoboCop's systems efficiency plummets, and he asks the resistance to summon Dr. Lazarus, one of the scientists who created him. Upon arrival she begins to treat him, deleting the Fourth Directive in the process. During an earlier raid on an armoury the resistance has picked up a jet-pack prototype, originally intended for RoboCop's use, which Lazarus modifies and upgrades.

After recovering from his injuries RoboCop conducts a one-man campaign against the Rehabs. He finds McDaggett and attempts to subdue him, but McDaggett is able to escape. McDagget then obtains information from a disgruntled resistance member (Stephen Root) regarding the location of the resistance fighters base. The base is then attacked by the Rehabs and most of the resistance members are either killed or taken prisoner. Nikko escapes with the help of Lazarus before she is captured and taken to the OCP headquarters as a prisoner.

RoboCop returns to the rebel base to find it abandoned. One of the Otomo ninjabots then arrives and attacks him. RoboCop experiences another power drain and his side-arm is destroyed, but eventually he is able to overcome his opponent. Meanwhile Nikko infiltrates the OCP building and assists Lazarus broadcast an improvised video, revealing that OCP is behind the outbreaks of criminality in the city and implicating them in the removal and termination of the Cadillac Heights residents. The broadcast causes OCP's stock to plunge dramatically, driving the company into total ruin.

McDaggett decides to execute an all-out strike against Cadillac Heights with the help of the Detroit City police department, but the outraged police officers refused to comply and instead defect to the resistance. As a result, McDaggett turns to hiring street gangs and hooligans to assist with his plans.

Having heard Lazarus' broadcast Robocop takes to the air using the jet-pack. As the combined forces of the Rehabs and street gangs are about to wipe out the rebels and Detroit Police, RoboCop mounts an aerial assault on the attackers, leading to their defeat. He then proceeds to the OCP building and confronts the waiting McDaggett. Robocop is then attacked, and nearly defeated, by two Otomo robots. Nikko and Lazarus succeed in reprogramming them using a wireless link from a laptop computer, however, forcing them to attack each other. This triggers a timed self-destruct sequence in both units, forcing Robocop to flee. Igniting his jet-pack the flaming discharge hits McDaggett's leg, immobilising him. Robocop escapes with Nikko and Lazarus, leaving McDaggett to perish in the blast while attempting to stop the self-destruct devices.

As Old Detroit is being cleaned up Kanemitsu arrives and confronts RoboCop and his group, while his translator (Doug Yasuda) tells the OCP president on Kanemitsu's behalf that he is fired. Kanemitsu then bows to RoboCop. The deposed OCP President turns to Robocop and says "Well, I gotta hand it to ya... what do they call you? Murphy, is it?" RoboCop replies, saying "My friends call me Murphy. You call me RoboCop."

• Robert John Burke – RoboCop / Alex J. Murphy
• Nancy Allen – Anne Lewis
• Mario Machado – Casey Wong
• Bruce Locke – Otomo
• Remy Ryan – Nikko Halloran
• Jodi Long – Keiko Halloran, Nikko's Mom
• John Posey – David Halloran, Nikko's Dad
• Elmore "Rip" Torn – OCP President
• Mako – Kanemitsu
• Felton Perry – OCP Vice President Donald Johnson
• John Castle – Commander Paul McDaggett
• Jill Hennessy – Dr. Marie Lazarus
• S.D. Nemeth – Bixby Snyder
• Robert DoQui – Sgt. Warren Reed
• Bradley Whitford – Fleck
• C. C. H. Pounder – Bertha
• Daniel von Bargen – Moreno
• Stanley Anderson – Zack
• Stephen Root – Coontz
• Eva LaRue Callahan – Debbie Dix
• Jeff Garlin – Donut Jerk
• Lee Arenberg – Hold-Up Man

The film was directed by Fred Dekker, a director primarily known for cult horror films (Night of the Creeps, The Monster Squad). Popular graphic novelist Frank Miller returned to write the screenplay for the film. Still optimistic that he could make an impression in Hollywood, Miller accepted the job of writing RoboCop 3, hoping that some of his excised ideas would make it into the second sequel. Major themes of the plot were taken from Miller's original (rejected) draft of RoboCop 2. Disillusioned after finding that his work was even more drastically altered than before, Miller left Hollywood until the 2005 adaptation of his work Sin City. “[Working on RoboCop 2 and 3] I learned the same lesson,” Miller said in 2005. “Don’t be the writer. The director’s got the power. The screenplay is a fire hydrant, and there’s a row of dogs around the block waiting for it.” Miller's original screenplay for RoboCop 2, and source for major ideas in Robocop 3, was later turned into a nine-part comic book series called Frank Miller's RoboCop.

The star of the previous films, Peter Weller, did not reprise the role, as he was starring in Naked Lunch.Robert John Burke was signed to play the cyborg character instead. The RoboCop suit Burke wore in the movie was originally built for RoboCop 2 (1990). Since Burke was taller than Weller, he complained that wearing it was painful after a short time. Other important casting changes had to be made for the third film. The actor who played the OCP CEO from the previous two films, Dan O'Herlihy, was absent from this film. The cast changes meant that Nancy Allen, Robert DoQui, and Felton Perry are the only three supporting cast actors to appear in all three films.

Pre-production problems continued, with the film aiming for a PG-13 rating, even after the success of the first two films which had been rated R. The profanity, graphic violence, and references to illicit drugs and prostitution were all reduced, or taken out altogether, causing the gritty and darkly gothic-science fiction environment of the first two films to be diluted.

RoboCop 3 went into production soon after RoboCop 2 was complete. Initially scheduled for release in the summer of 1992, RoboCop 3 would languish on the shelf until the following year as Orion Pictures went through bankruptcy and was bought out. RoboCop 3 earned $4.3 million on its opening weekend, ending its run with $10.6 million domestically, far short of recouping its estimated $22 million production budget.

Music

After RoboCop 2's score which was composed by Leonard Rosenman, the RoboCop original composer Basil Poledouris returned to do the soundtrack score and brought back many of the RoboCop themes that were missing from RoboCop 2.

RoboCop 3 was panned by critics and fans of the previous two films, and is widely considered to be the poorest of the series. Rotten Tomatoes lists RoboCop 3 at a 4% rating (Rotten) across 28 reviews. Richard Harrington from the Washington Post says, "...it's hardly riveting and often it's downright silly. The sets and effects betray their downsized budget."

Chicago Sun Times critic Roger Ebert gives the film 1½ stars, disputing the characters's longevity and comparing the series to the Detroit car manufacturing industry, "Why do they persist in making these retreads? Because 'RoboCop' is a brand name, I guess, and this is this year's new model. It's an old tradition in Detroit to take an old design and slap on some fresh chrome."

David Nusair from Reel Film Reviews, however, rates the film as 2½ stars, stating, "The best one could hope for is a movie that's not an ordeal to sit through, and on that level, RoboCop 3 certainly excels. When placed side-by-side with the original, the film doesn't quite hold up. But, at the very least, RoboCop 3 works as a popcorn movie—something part two couldn't even manage."

Other points of criticism in this movie include curtailing the graphic violence of the first two films, less humor and the absence of Peter Weller in the title role (replaced by Robert John Burke).

RoboCop 3 has an average score on Rotten Tomatoes of 3.1/10.