With the impending ice age almost upon them, a mismatched trio of prehistoric critters – Manny the woolly mammoth, Diego the saber-toothed tiger and Sid the giant sloth – find an orphaned infant and decide to return it to its human parents. Along the way, the unlikely allies become friends but, when enemies attack, their quest takes on far nobler aims.
Times are changing for Manny the moody mammoth, Sid the motor mouthed sloth and Diego the crafty saber-toothed tiger. Life heats up for our heroes when they meet some new and none-too-friendly neighbors – the mighty dinosaurs.
Manny, Sid, and Diego are currently living in a large valley surrounded by an enormously high ice wall on all sides. However, the trio discovers that the ice wall is actually a dam that is barely holding a massive body of water that could flood the valley to nearly a mile underwater. A vulture tells them that there is a boat at the other end of the valley that may save them all, but they only have three days to reach it or die. Manny is also having trouble fearing the fact that he may be the last mammoth left.
While Scrat inadvertently causes the break up of Pangaea, Manny and Ellie are forced to deal with the trials and tribulations of their teenage daughter Peaches, who has trouble fitting in with her peers. Ellie tries to support her daughter, but Manny becomes exceedingly overprotective. Meanwhile, Sid's family returns, but only long enough to drop off the elderly Granny before abandoning them both. Shortly after, a sudden continental break-up separates Manny from The Herd. Trapped on a moving chunk of ice with Sid, Granny, and Diego, Manny has no choice but to ride out the current. Meanwhile, a giant land shift encroaches on Ellie, Peaches, and those remaining on land, causing them to make their way towards a land bridge.
When Scrat's acorn sends an asteroid to Earth, the Herd must find a way to stop the asteroid from hitting Earth with the help of a returning friend.
The fearless one-eyed weasel Buck teams up mischievous possum brothers Crash & Eddie as they head off on a new adventure into Buck's home: The Dinosaur World.
Christmas has come and Scrat eyes a beaver assembling a cache of foods, among them an acorn: Scrat sneaks in and takes the acorn, along with others he finds in the area set up as decorations: he ties a large stockpile of them on a piece of bark and tries to leave with them, but they break out and leave him with nothing. Meanwhile, Manny brings the Christmas Rock out of storage, to Ellie's delight: the rock is intended as a surprise for Peaches, who comes sliding down a snow slope in a snowball fight with Crash and Eddie. Manny reveals that the Christmas Rock is the same one from his childhood, a family heirloom, and important as it lets Santa Claus find them to deliver presents.
Three months after the events of the Ice Age: Continental Drift, Manny and his crew get ready for Easter. With Ellie struggles to make the decorations single-handedly, Manny and Diego try to watch some eagle fights between an eagle and different animals, Crash and Eddie try repeated unsuccessful attempts to prank Peaches (starting the first April Fools' Day), who wants to spend Easter with her friends, and Scrat, after he excavated in the underground from the Death Valley to the new herd's Valley and founded his acorn again, once again loses his acorn when it becomes a tree. In the meantime, Sid decides to look after eggs for the owners of them, much to the scorn of Manny and Diego.