In a dystopian future, Detroit is on the verge of collapse due to financial mismanagement and a high crime rate. The city signs a deal with the megacorporation Omni Consumer Products (OCP) to run Detroit’s police department in exchange for letting OCP rebuild run-down sections of the city into a high-end utopia. Senior Vice President Dick Jones demonstrates a new law enforcement robot, ED-209. However, the robot malfunctions, killing an executive. Bob Morton, an ambitious executive, uses the opportunity to introduce his own experimental cyborg design, RoboCop. The chairman is dismayed at the ED-209 failure and approves Morton’s plan, to Jones’ anger.
On patrol in the violent Metro West precinct, officers Alex Murphy and Anne Lewis pursue a notorious gang after an armed robbery. Investigating their hideout, an abandoned steel mill, Murphy kills one of the gang members, but is ambushed by the leader, Clarence Boddicker. Boddicker and his accomplices shoot Murphy repeatedly with shotguns, until Boddicker shoots him through the head. Lewis arrives too late to help. Murphy is evacuated by helicopter but dies in the trauma unit.
OCP claims Murphy’s body and converts it into RoboCop. The cyborg is programmed with three Prime Directives: serve the public trust; protect the innocent; and uphold the law. RoboCop is assigned to Metro West, where he begins a brutally efficient campaign against crime. However, though Murphy’s memory was wiped, RoboCop begins to remember scenes from Murphy’s life, including his death. Lewis confirms to RoboCop that he is Murphy, to his shock. On patrol, RoboCop foils Emil’s armed robbery; Emil recognizes Murphy’s mannerisms, furthering RoboCop’s memory recall. RoboCop uses the police database to identify the gang members and locate his home, now abandoned. Meanwhile, at the behest of Jones, Boddicker murders Morton.
RoboCop locates Boddicker at a cocaine factory, where he kills almost everyone present and captures Boddicker. RoboCop brutalizes Boddicker, but before RoboCop can kill him, Boddicker reveals that he is in Jones’s employ. Depositing Boddicker at Metro West, RoboCop heads to OCP Tower to arrest Jones for aiding Boddicker. However, when RoboCop attempts to arrest Jones, RoboCop unwittingly activates Directive 4, implanted by Jones himself: “Any attempt to arrest a senior officer of OCP results in shutdown”. Jones admits his culpability in Morton’s death, and tries to kill RoboCop with an ED-209 unit. However, RoboCop escapes to the garage, where police ambush him. Lewis finds RoboCop and helps him escape to the abandoned steel mill to repair himself.
The police, angered by OCP’s underfunding and short-staffing, call a strike, and Detroit descends into chaos. Jones, having freed Boddicker and his gang, provides them with heavy weapons and a tracking system for RoboCop, then sends them out to destroy RoboCop. The gang arrives at the steel mill, but they are dispatched by RoboCop and Lewis. The final confrontation with Boddicker ends with RoboCop violently stabbing him in the throat with the computer data spike installed in his fist.
RoboCop returns to OCP Tower, destroying the ED-209 at the door with Boddicker’s weapon. He confronts Jones at a board meeting, revealing Directive 4 and his recording of Jones’ confession. Jones grabs a gun and takes the OCP chairman, planning to escape via helicopter with him as hostage. The chairman clues in and fires Jones, making Directive 4 irrelevant, allowing RoboCop to shoot him; he falls from the tower to his death. Impressed and thankful for saving his life, the chairman asks RoboCop’s name; he replies “Murphy”, indicating he has regained a sense of his humanity.