The AJ Birthday Party (Abbreviated form of Animal Jam Birthday Party) was created to celebrate Animal Jam's yearly anniversary of when it was officially released after Beta Testing ended. It was first introduced on September 13, 2012, and it is an annual party, which means it comes around for a limited time each year. This party can be accessed by any Jammer.
The AJ Birthday Party seems to entirely take place on a triple-layered cake. Several scoops of ice cream can be seen around it, along with a few cookies and what appears to be a chocolate river. On the top layer, rests a number candle, representing how old Animal Jam is. Along the top of the cake, there is an area where jammers can sink into the cake. Along the bottom layer is a series of bronze statues representing the Alphas of Jamaa, many of whom have yet to be formally introduced.
This party plays the Birthday Bash song in the background. The music begins to play the Birthday Song melody in a slow and heavy tempo, which then transitions into a faster and lighter tempo.
This party has three shops where Jammers can buy items that are mostly related to the Alphas: a clothing shop on the left side of the second layer, a music shop on the left side of the first layer, and a den item shop on the right of the first layer. There are several striped candles on the cake that give Jammers a holdable ice cream cone to carry around when they click on the flame. Jammers can also get a holdable cake slice to carry by clicking on the flame of the number candle at the top.
- The giant cake at the party is usually brown, but 2013's version of the party used a purple cake instead.
- The clothing shop and the music shop are more recent shop additions to the AJ Birthday Party that were not available in the original party.
- There has been a birthday cake code introduced every time AJ's birthday came around (except during 2017), usually beginning with "AJBDAY" followed by the number of years Animal Jam has existed since the year of the party's hosting.
- This party offered the first glimpses of many "secondary" Alphas that were not seen anywhere else in the game.
- There was once a glitch that allowed Jammers to enter the sky areas of this party with land animals, but it was later fixed.
- The original version of this party did not play any background music.