The last quarter saw four releases of the Philippine Marine Biodiversity series. The October 17, 2011 issue featured the 1p Picasso Trigger, 2p Marmorated Cone, 5p Copper-band Butterflyfish, 10p Triton Trumpet, 20p Bennett's Feather Star, and the 30p Eibl's Angelfish.
October 25, 2011 saw the issuance of the second set of definitives. These were the 4p Blue-faced Angelfish, 7p Murex Shell and the 100p Regal Tang.
The third was on November 4, 2011 that featured the 9p Polyclad Flatworm, 25p Oriental Sweetlips, and the 35p Kunie's Chromodoria.
The last set came out on November 11, 2011 and featured the 13p Valentine Puffer, 17p Polka-dot Grouper, and the 40p Royal Empress Angelfish.
To celebrate the United Nations Day, Philpost came out on October 24, 2011 stamps that highlighted the International Year of the Forests. The stamps were valued at 7p each and in a se-tenant pair.
The design featured Batlag Falls and a big tree in Pansol, Laguna.
On November 10, 2011 the second issue showcasing Dia Del Galleon was released. The stamps came out on a se-tenant strip of 3 valued at 7p each. A 28p souvenir sheet and an 84p miniature sheet of 12 added to the set. The stamps featured a galleon ship with a map of the Philippines, a galleon ship with a map of Mexico and a galleon ship with a map of Spain.
The following day, to celebrate the 2011 National Stamp Collecting Month, a se-tenant block of 4 stamps valued at 7p each came out together with a 28p souvenir sheet. The stamps highlighted the works of Filipino Artist Hernando R. Ocampo. The stamps showed the following paintings: Homage to Jose Rizal (1976), Break of Day (1948), Summer in September (1975), Mother and Child (1954), Fiesta (1957), Abstraction #15, 17 (1976), Kasaysayan ng Lahi (1974), and Abstraction #22, 26 (1976).
The National Bureau of Investigation (NBI) celebrated its 75th year in 2011. To commemorate the event, Philpost issued a se-tenant block of 4 stamps with a value of 7p each on November 14, 2011. The designs featured the official seal of the NBI, Justice Yulo and President Manuel L. Quezon (Forefathers of NBI), President Manuel Roxas With First NBI Director, J. Pardo de Tavera, a magnifying glass and a laptop.
The traditional Pasko (Christmas) stamps were issued on November 25, 2011. The se-tenant block of 4 stamps were valued at 7p each. The stamps depicted Christmas bells, Christmas flowers, toys and gifts and a Christmas lantern (Parol).
On December 5, 2011 Philpost released the 2012 Year of the Dragon stamp set. The set included two stamps valued at 7p and 30p, an 84p souvenir sheet, a 70p miniature sheet of 10, a 300p miniature sheet of 10 and a 74p souvenir sheet.
A 7p stamp commemorating the 110th anniversary of the Office of the Solicitor General was issued on December 15, 2011. The design showed the official seal of the Office of the Solicitor General.
Also on the same day, the Philippine Endemic Frogs set was also issued. A se-tenant block of 4 stamps, a 28p souvenir sheet and a 112p miniature sheet of 18 completed the collection. The stamps featured the Philippine Spiny Cinnamon Frog, Philippine Pygmy Forest Frog, Philippine Flat-headed Frog, Luzon Limestone Forest Frog, Gliding Tree Frog, Northern Luzon Tree-hole Frog, Taylor's Igorot Frog, and Mary Inger's Wart Frog.