Metal Gear Solid: Portable Ops Plus (officially abbreviated MPO+) is a stand-alone expansion of the original MPO, focused primarily on online play. It was first announced on July 17, 2007 and was released in Japan on September 20, 2007, in North America on November 13, 2007, in Europe on March 28, 2008, and in Australia on April 4, 2008. A digital version was released on the PlayStation Store in 2009.

MPO+ includes new general and unique character types from other MGS titles, as well as new items and weapons, new multiplayer maps, and new game modes. While MPO+ does not require the original MPO, players who have save data from the original game can transfer their squad to the expansion and any unique character that the players recruit in the original MPO since their initial save file was created will be added automatically in MPO+ if detected.