The first trailer, titled 'Power, Power, Power!', features fuzzy images displayed on a black and white television set. It is accompanied by an official tweet saying: "Power, power, power, power! It's always the first priority.' – Edward Richtofen."
The second video appears to show in-game footage of zombified hospital patients wrecking a bus. It is accompanied by another tweet saying: "When you hear it... it may already be too late."
Treyarch has confirmed that it will unveil the new Zombies mode on September 26.
A recent Amazon listing, which has since been removed, suggests that zombies will appear in multiplayer, and as a campaign option.
The game's developers have previously teased the mode via a series of images on social network sites. An early image released on Twitter said: "Zombies are coming... Where's your shotgun?"
More recently, the game's official Facebook page featured a "Welcome to Nuketown" road sign with the word "Zombies" scrawled in blood.
Announced earlier this year, Black Ops 2 is set during a 21st-century Cold War and will release on November 13 on Xbox 360, PS3 and PC. A Wii U version will follow.
The game's campaign will feature usable drones and horses, as well as a robot enemy forced to fight in a devastated Los Angeles.
Multiplayer, meanwhile, will utilise a new scoring system in place of the traditional killstreaks, with dozens of rewards on offer for high-scoring players.
Revealed at gamescom, core streaks have been incorporated to allow players to rack up bonuses for completing objectives as well as making kills. Capturing flags, defending teammates and earning assist points will boost the metre significantly.
Bonuses include the option to call in vehicle support, which includes assistance from high-tech machinery such as VTOL Warships, Lodestars, X9 Units, the Humvee-esque Guardians and more.
> Read our preview of Black Ops 2
Watch the Call of Duty: Black Ops 2 multiplayer trailer below: