Big Baboon has a dark brown body and scruffy tail. His stomach is a dark cream. The palms of his hands are pink, as are his feet and face. He has a long, dark pink snout and his chin has a few stray hairs sticking out from underneath. Under his eyes are purple wrinkles, and his eyebrows are thick and beige. Around his neck and over his head is a brown-white fluffy mane.
Big Baboon has been shown as a somewhat confident leader, though his ideas are not always the best. He is very stubborn, and once his mind is set on something, he will not be persuaded to change his stance unless drastic measures are involved. He is willing to offer information to those who need it, though, like most baboons, he enjoys hurling fruit at others.
Big Baboon chases Fuli, for reasons unknown at first. He and his troop trample over Bunga in their pursuit, trying to catch the agile cheetah. Eventually, they wind up smashing into Beshte, who was set up to block the baboons by Kion. After thanking them for the help, Fuli turns to Big Baboon and his troop and apologises for saying that they looked funny when they scratched their heads, assuring them that she wasn't trying to be mean by saying it. Big Baboon peers up at her, telling her that her apology has been accepted before falling flat on his back.
Big Baboon and his troop have climbed up a slowly breaking tree in order to stay dry. When Kion asks him and the rest of the baboons to come down, he refuses, stating that they are dry up there. He then assures his troop that as long as they stay dry, everything will be okay. However, Ono points out that the tree is breaking, and a female baboon in the troop confirms the egret's words as true.
Desperate to get them down as Beshte struggles to keep the tree up, Kion sends Bunga up to get them down. Bunga does so, and lets loose a blast of flatulence directly into the troop, causing everyone to leap off the tree. Big Baboon lands safely on Fuli with another baboon. But When she asks if he plans on getting off, he informs her that he will only get off once it stops raining, causing her further agitation towards their actions.
Fuli attempts to return Baby Baboon to Big Baboon in Nyani Grove. Big Baboon laughs before he informs her that the baby is from their neighbors, the baboons in Mapango Cliffs. Before she leaves, he asks if will deliver a message to the cliff baboons. She pauses, and he and his troop immediately bombard her with baobabs. After she leaves, he asks whose turn it is to pick up the "throwing-fruit." When his companions all point at each other, he rolls his eyes and mutters "baboons."
When Kifaru the rhino loses his tickbird, Mwenzi, his poor eyesight drives him straight into Big Baboon Tree. In the commotion, Big Baboon leaps down from the tree and runs across Nyani Grove to escape.
Later, Rafiki paints his picture alongside Mbeya, who has sat on Zazu after a misunderstanding. When the Lion Guard arrive, they find out that Mbeya had knocked into Big Baboon by mistake, and Big Baboon had insulted him. After teasing him about having Zazu's feathers on his backside, he apologizes for the harsh word, and Mbeya accepts.
Later, he hears from Kion that Makuu passed away in an accident. When Makuu is revealed to be alive, he gasps in shock. He gasps again when it turns out that Twiga and Vuruga Vuruga were behind the scheme. He rejoices when Makuu is forgiving towards them both, and allows the summit to continue.
Big Baboon runs from Janja's Clan, ordering his troop to follow the elephants, who are looking for a new water source for the dry season. Once saved, he eagerly awaits Ma Tembo's finding of the new water source, cheering her on repeatedly.