Ullu is primarily white, with gray patterns along her chest, wings and head. She has light grey eyes, a small, dark gray beak, and two white feathers on each side of her head. Her talons are dark gray with black claws.
Ullu is shown to be a helpful owl, warning the Night Pride whenever there is a potential threat to the Tree of Life.
Ullu spots the Lion Guard from her tree branch and suspects that they are a threat, so she warns the Night Pride. She brings the Night Pride to the pass, where there is now a rockslide. Rani thanks her for warning them, and Ullu flies off.
Ullu overhears Makcuha's Army and goes to reports this to Rani and the Night Pride. Meanwhile, the rest of the Guard find Kion and tell him about Ullu fetching Rani. The next morning, Ullu arrives at Dirisha and tells Nirmala that Rani needs her since the predators are back.
Ullu overhears "Granny Ginterbong" pleading for help. Unaware that she is only pretending to be threatened, Ullu guides the Night Pride to the pass, where they rescue her from the predators.
Later at sunrise, Ullu hears Granny Ginterbong crying for help from Ciso River, and Rani tells her to pass along a message to the Lion Guard. Ullu finds and wakes them, informing them Granny Ginterbong is being "attacked" at the icy river. However, Ono soon deduces Granny is working with Makucha. Kion tells Ullu to go warn the Night Pride that Granny is a decoy, which she does.
Ullu tells Rani that she just spotted a cheetah coming through the pass. It turns out to be Azaad, who helped Janja and Jasiri find their way to the Tree of Life to warn the Lion Guard that Zira has returned to the Pride Lands with two of her fully grown spawn.