|Season Run||October 29, 2011 - March 31, 2012|
|Host|| Toni Gonzaga|
|Previous Season||Pinoy Big Brother: Teen Clash 2010|
|Next Season||Pinoy Big Brother: Teen Edition 4|
Pinoy Big Brother: Unlimited is the fourth season and the ninth series overall of Pinoy Big Brother that aired on ABS-CBN from October 29, 2011. Toni Gonzaga and Bianca Gonzales reprised their hosting stints for the show, together with PBB Teen Edition Plus ex-housemate Robi Domingo. The season ended on March 31, 2012 after 155 days, breaking Double Up's record for the longest duration by three more weeks and also ranked as one of the show's longest seasons worldwide, only surpassed by a number of seasons held in Germany. It is the first regular season with a male winner: Slater Young.
For the season, the exterior of the House was slightly tweaked to have slotted walls and minor modifications, but still keeping the yellow and blue color scheme. There are five areas for this season: four Houses and a special area. Two of the houses, the Industrial and Luxury Houses, are connected via a secret hallway first revealed on Day 22 and fully opened on Day 65.
- Slums: First occupied on opening night, the Slums was made to look like a typical squatters' area in many urban areas in the Philippines. This was done to let the housemates experience the same living conditions as 15 million Filipinos who live in such areas, based from a typical answer during auditions of experiencing typical Filipino life. This House was demolished on Day 22.
- Industrial House: The interior of the second House follows the regular House layout and its accompanying amenities. It is further given an "industrial" feel with steel, wooden, and brick walls. Unlike previous seasons, however, this House has no yard area. The house was opened on Day 8 to house another group of housemates and was closed down on Day 77.
- Luxury House: Also called the Mansion, the third House is exquisitely furnished and brightly lit. Like the Industrial House, this House also has no yard area, although sunlight somehow passes through a curtain. This house was opened on Day 22 when the two groups of housemates merged together.
- Resort: Located adjacent to the Luxury House, this area is sophisticated with the inclusion of the pool and a jacuzzi in the beach-themed Garden area. It is used as a venue for special occasions and tasks. This area was opened on Day 15 and the door to the resort (hidden under a curtain in the Luxury House) was opened on Day 65.
- Hacienda: Located at the activity area, the Hacienda is modelled after a typical plantation in the Philippines by featuring several plants. It contains a large hut where the housemates would live in. This House was opened on Day 128.
Unlimited Season Twists
Reserved housemates — short-listed auditionees are given another chance to become official housemates.
Unli-Day/Unli-Night —The show features two houses, each containing a different set of housemates. To accommodate both, a second main program, Unli-Day, was aired in the afternoons to focus on the events in the Industrial House. The setup only applies to weekdays; on weekends, nomination and eviction nights, and special shows, the primetime program would cover both Houses. With the closure of the Industrial House on Week 11, Unli-Day was directed towards covering events in the active House(s) while the host has an interview session with former housemates.
House Swaps — Housemates will be made to swap houses and group members as instructed by Big Brother.
SE Voting System — The public votes to save or evict a housemate. The housemate with the lowest net votes, Save and Evict votes combined, is evicted. This voting system was stopped after the fourth eviction round.
Head of Household — Housemates compete against each other to be granted immunity in the coming nomination.
House Competitions — For ten weeks, the two Houses compete in weekly major competitions with PHP150,000 at stake in each. At the end of those ten weeks, the cash accumulated by each team would be shared among the final five housemates in each House. The teams would also compete in "mini-battles" wherein the winning team would be given minor rewards.
Intensity 7 — On Day 71, the remaining 20 housemates, 11 from Team High-Voltage and nine from Team Wayuk, were put-up for 24-hour public voting. The top five housemates from each team will be safe from elimination on Day 78, where six housemates will be evicted from the house. A sequel twist, called the Aftershock, would test the remaining housemates further. Various Nominations – Various nomination processes were implemented as per Big Brother. See Nomination history for details.
Overnight Voting - In some eviction nights, people will only be given 24 hours to vote for their favorite housemate.
House Players - An evicted housemate will remain in the house to test the remaining official housemates through tasks set by Big Brother and the audience.
Wildcard Housemate - An evicted housemate will have a chance to come back on the roster of housemates.
Power of One - Starting the 13th eviction, the public may only vote once per day per mobile phone number.
Big Shot for the Big Slot - The final five housemates are given the chance to have a fifth slot in the finale by completing a shooting task.
|Civilian||1 · 2 · 3 · 4 · 8|
|Combined||5 · 6 · 7|
|Celebrity||1 · 2|
|Teen||1 · 2 · 3 · 4|
|Big Brother Seasons|