The Elder Princess Shroob resembles her sister, as she is a humanoid Shroob wearing a magenta dress, a silver crown with a black gem in the center, and green earrings (although she has no ears). However, she is bigger and has a hunched body, crooked jaw, and pincer hands.

In her true form, the Elder Princess Shroob becomes much larger and the gem on her crown is orange instead of black. Her arms have been replaced with tentacles, and her dress has been tattered, especially at the bottom, revealing her legs, which consist of multiple tentacles.

The Elder Princess Shroob appears too briefly for her personality to be explored in-depth, but her short appearance does give some basic traits of the Shroob monarch. The Elder Princess Shroob seems to have cared a lot for her sister and swears her life into avenging Princess Shroob's death: indeed, the Elder Princess Shroob never makes any mention of her own ambitions for power in-game. However, she still seems to have had many of the bad traits Super Mario villains tend to show. She seems to be deceptive and manipulative, as shown by her convincing the Bros. to repair the Cobalt Star under the guise of it being a 'star sprite': she also does not appear to be particularly appreciative and is highly condescending, as she then responds to this favor by promising to bring death to the Bros and insults them repeatedly in the process, referring to them as "foolish mushroom heads." In addition, in spite of the confidence she shows in her people's abilities during her final speech, she does not visibly show any concern at all for her own people.

Whenever a Shroob saucer performs a task for her, she knocks it away, even for simple tasks like bringing her a drink of Vim; when she turns into a beast, she is even more destructive, shooting down her own saucers so that they hit the Mario Bros. Nonetheless, she has confidence in the success in the invasion of the Shroobs, as evidenced by her last words to the Mario Bros. where she stated that, even with her defeat, the Shroobs will ultimately be victorious over the Mushroom Kingdom, though she is proven wrong afterwards when the Shroobs' weakness is discovered.