Set in August 2006, two months before the events of the first film, Katie's sister Kristi and her family reside in Carlsbad, California, where they experience strange activity after her baby, named Hunter, is born.

Set in September 1988, it focuses on a younger Katie and Kristi, who live with their mother Julie and her boyfriend, Dennis, in Santa Rosa, California.

The family began to experience hauntings, concerning Alex's adopted brother, Wyatt, after Katie and her mysterious son, Robbie, move in across the street.

Set in June 2012, the film follows a Latino community in Oxnard, California, where a group of high school graduates deal with the demon of a mysterious cult which has "marked" one of them.

The family begins to be haunted by the demon when the daughter, Leila, is targeted as she was born on the same date as Hunter from Paranormal Activity 2.

Peli took a year to prepare his own house for shooting, going so far as to repaint the walls, add furniture, put in a carpet, and build a stairwell.

The phenomena in the film take place largely at night—the vulnerability of being asleep, Peli reasoned, taps into a human being's most primal fear, stating, "If something is lurking in your home there's not much you can do about it."

Attempting to focus on believability rather than action and gore, Peli chose to shoot the picture with a home video camera.

In casting the movie, Peli auditioned "a few hundred people" before finally meeting Katie Featherston and Micah Sloat.

During a guest appearance on The Jay Leno Show on November 3, 2009, Sloat and Featherston explained they each saw the casting call on LACasting.

"It was a very intense week", Peli recalled, stating that the film would be shot day and night, edited at the same time, and would have the visual effects applied to it as the acting footage was being finalized.

Paranormal Activity 3 and 4 were directed by Henry Joost and Ariel Schulman, documentary filmmakers who were well-known for their feature debut Catfish.

Oren Peli, the creator of the franchise, returned to produce the film, while Christopher Landon, a screenwriter who had worked on the prior three entries in the series, served as the writer and director.

In late September 2013, Paramount hired Almanac writers Jason Pagan and Andrew Stark to write the screenplay.

In December 2009, a short digital comic entitled Paranormal Activity: The Search for Katie was released for the iPhone.

[43] A video game Paranormal Activity: Found Footage developed by DarkStone Digital and published by DreadXP will be released sometime in 2026.

A stage play based on the films also called Paranormal Activity written by Levi Holloway and directed by Felix Barrett premiered at the Courtyard at Leeds Playhouse on July 4, 2024, for a limited run until August 3.

[46] Paranormal Activity: True Tales of Possession was released in July 2024 on Audible in collaboration with Paramount Pictures Audio, where the lead actors of the first film Katie Featherston and Micah Sloat examining real-life stories of demonic possession, tracing the phenomenon from its earliest known accounts to its modern-day headlines.