Achttien jaar voor de gebeurtenissen van deel 1 en 2 volgen we Katie en haar zus Kristi in het huis van hun ouders. Na verloop van tijd merkt Dennis dat Kristi zich raar begint te gedragen nadat ze heeft beweerd een onzichtbare vriend te hebben, genaamd Toby. Op aanraden van Randy plaatst Dennis een aantal camera's in het huis om te zien of er ook echt iets rondspookt. Ze doen een schokkende ontdekking...
Nee, helaas is Paranormal Activity 3 nog niet beschikbaar op Netflix in Nederland.
| Sound | Stephen P. Robinson | Sound Designer |
| Crew | James G. Brill | Transportation Coordinator |
| Crew | Lynn Johnson | Set Medic |
| Sound | Margit Pfeiffer | Foley Editor |
| Crew | Nikki Hester-Jose | Stunt Double |
| Crew | Liisa Cohen | Utility Stunts |
| Production | Sarah Domeier Lindo | Casting Assistant |
| Directing | Matt Smith | Second Second Assistant Director |
| Lighting | Derek Touvell | Electrician |
| Crew | Kelli Barksdale | Stunts |
| Crew | Nicholas King | Stunts |
| Crew | Ator Tamras | Stunt Double |
| Directing | Jaysene Overton | Second Second Assistant Director |
| Crew | Chris J. King | Stunts |
| Crew | Hernan Hernandez | Craft Service |
| Production | Claire Simon | Casting |
| Sound | Paul Stevenson | Foley Artist |
| Crew | Seth Duhame | Stunt Double |
| Camera | Keith Dunkerley | Camera Operator |
| Production | Billy Stimson | Production Assistant |
| Crew | Meegan E. Godfrey | Stunts |
| Crew | Meegan E. Godfrey | Stunt Double |
| Crew | Craig Jensen | Stunts |
| Crew | Michael R. King | Stunts |
| Sound | Daniel S. Irwin | Dialogue Editor |
| Crew | James Armstrong | Stunts |
| Camera | Olga Matlin | Grip |
| Costume & Make-Up | Ryan Lennon | Costumer |
| Crew | Jason Messersmith | Transportation Captain |
| Crew | Daniel Browning Smith | Stunts |
| Production | Christine Kromer | Casting |
| Costume & Make-Up | Rebecca M. Graves | Costumer |
| Directing | James Moran | First Assistant Director |
| Sound | Tim D. Lloyd | Boom Operator |
| Production | Alexa L. Fogel | Casting |
| Crew | Pablo C. Herrera | Craft Service |
| Directing | Marc Newland | Second Assistant Director |
| Crew | Steven Stone | Stunts |
| Camera | Daniel C. McFadden | Still Photographer |
| Production | Murray Miller | Location Manager |
| Sound | Michael Hertlein | Dialogue Editor |
| Sound | Zsolt Magyar | Sound Mixer |
| Production | David Thornsberry | Location Manager |
| Production | Erin Vitali | Production Assistant |
| Crew | Emily Brobst | Stunt Double |
| Art | Kelly Berry | Set Decoration |
| Production | Steven Schneider | Producer |
| Production | Oren Peli | Producer |
| Art | Jennifer Spence | Production Design |
| Production | Jason Blum | Producer |
| Writing | Christopher Landon | Writer |
| Editing | Gregory Plotkin | Editor |
| Directing | Ariel Schulman | Director |
| Directing | Henry Joost | Director |
| Costume & Make-Up | Leah Butler | Costume Design |
| Production | Terri Taylor | Casting |
| Production | Christopher Landon | Co-Producer |
| Crew | Zachery Alexander | Property Master |
| Directing | Diane Weiss | Script Supervisor |
| Visual Effects | Jamie Dixon | Visual Effects Supervisor |
| Crew | Thomas Mertz | Special Effects Coordinator |
| Visual Effects | Michelle Eisenreich | Visual Effects Producer |
| Production | John McAlary | Casting Associate |
| Crew | Robert Malina | Visual Effects Editor |
| Costume & Make-Up | Kymber Blake | Makeup Department Head |
| Costume & Make-Up | Linda Huse | Costume Supervisor |
| Costume & Make-Up | Renee J. Vaca | Hair Department Head |
| Costume & Make-Up | Paula Jane Hamilton | Makeup Artist |
| Camera | Magdalena Górka | Director of Photography |
| Production | Akiva Goldsman | Executive Producer |
