Embodiments of the invention relate to a customizable modular pet house and entertainment system. In one general embodiment of the invention, a pet house comprises a module formed from a sheet of self-supporting material. The module comprises a top panel, a bottom panel, and four side panels. At least one of the panels may have at least one of a removable transition panel, a removable door panel, and perimeter of a removable window panel. Optional accessories include a top accessory panel, a side accessory panel, and an accessory bracket. More than one modular pet house may be joined together to form an extended structure. Embodiments of the invention have interior spaces and apertures sized for admittance of a common house cat.