The first season of the American television series Person of Interest premiered on September 22, 2011, and ended on May 17, 2012. The season is produced by Kilter Films, Bad Robot, and Warner Bros. Television, with Jonathan Nolan, Greg Plageman, J. J. Abrams, and Bryan Burk serving as executive producers and Plageman serving as showrunner.

The series was ordered to series in May 2011 and stars Jim Caviezel, Taraji P. Henson, Kevin Chapman, and Michael Emerson. The series revolves around a mysterious reclusive billionaire computer programmer, Harold Finch, who has developed a computer program for the federal government known as "the Machine" that is capable of collating all sources of information to predict terrorist acts and to identify people planning them. The Machine also identifies perpetrators and victims of other premeditated deadly crimes; however, because the government considers these "irrelevant", Finch programs the Machine to delete this information each night and programs the Machine to notify him secretly of the "irrelevant" numbers. Finch recruits John Reese, a former Green Beret and CIA agent, now presumed dead – to investigate the people identified by the numbers the Machine has provided, and to act accordingly.

The season premiered with a 13-episode order before being given a 9-episode back-order in October 2011. In March 2012, one more episode was ordered, bringing its total to 23 episodes. The series premiere garnered 13.33 million viewers with a 3.1/8 ratings share in the 18–49 demographics, winning its time slot. The season ended with an average of 14.34 million viewers, ranking as the 13th most watched series of the season. The season initially received generally positive reviews from critics, who praised its potential while some criticized its characterization and lack of character development. Reception grew more positive as the season went on, with critics highlighting the exploration of mass surveillance and repercussions of its actions, with the season finale particularly receiving acclaim. In March 2012, CBS renewed the series for a second season.

John Reese (Jim Caviezel), a former Special Forces soldier and CIA operative, is burnt out and presumed dead, living as a vagrant in New York City. He is approached by Harold Finch (Michael Emerson), a reclusive billionaire software genius who built a computer system for the U.S. government after September 11, 2001 which monitors all electronic communications and surveillance video feeds, in order to predict future terrorist activities. The computer – known informally as "the Machine", and funded under the codename "Northern Lights" – also predicts other lethal crimes as well, but being irrelevant to national security these were deleted daily.

To prevent abuse of its capabilities, Finch had programmed the Machine to only provide an identity of a person predicted to be involved in an imminent lethal crime, in the form of a Social Security number, but no details of the crime or whether the person of interest is a perpetrator or victim. Those involved in creating Northern Lights, such as Finch's best friend and business partner Nathan Ingram, have largely been killed by the authorities to hide the project's existence. Finch realises that knowledge of the victims deemed "irrelevant" would have saved his partner, and decides to act covertly on the non-terrorism predictions. He hires Reese to conduct surveillance and intervene in these cases. Finch and Reese attempt to understand the threat to, or by, people whose numbers the Machine provides, and try to stop the crime from occurring. They are helped by NYPD Detectives Lionel Fusco (Kevin Chapman), a formerly-corrupt officer whom Reese coerces into helping them, and Joss Carter (Taraji P. Henson), who initially investigates Reese for his vigilante activities.

The project started in September 2010 when NBC ordered a put pilot for a series called Odd Jobs after winning a bidding war with ABC. The project had Josh Appelbaum and André Nemec as writers, J. J. Abrams and Bryan Burk as executive producer through their production company Bad Robot and would star Michael Emerson and Terry O'Quinn, both previously worked with Abrams and Burk on Lost. Around this time, Jonathan Nolan was also working on an undisclosed series for CBS with Bad Robot serving as executive producer. In January 2011, NBC announced that Odd Jobs would roll on the next season after delays in the production of the series.

In February 2011, CBS picked up Nolan's series, now titled Person of Interest, ordering a pilot order. A few days later, David Semel was announced to direct the pilot for the series. In April 2011, Greg Plageman joined the series as executive producer and would also serve as showrunner. By May 2011, Deadline Hollywood reported that the pilot was "gaining momentum" compared to other drama series on CBS. A week later, the site reported that it was in a "frontrunner status" to be picked up. In May 13, 2011, CBS officially picked up the pilot to series, ordering a 13-episode season.

Michael Emerson was the first actor to join the series in February 2011, starring as a "mysterious billionaire who hires a special ops agent". Emerson dropped out of Odd Jobs and was also offered a role in Once Upon a Time. Emerson took the role to avoid being "typecast" as his previous role on Lost as Ben Linus. In March 2011, Jim Caviezel and Taraji P. Henson joined as series regulars, with Caviezel playing the lead character, John Reese, while Henson was set to play a homicide detective Joss Carter. Caviezel took the role as his character was "searching for a purpose. I think, like it hit me, it's going to hit other people there's something besides all the technology in the story." By April 2011, Kevin Chapman also joined the series.