Mbeya is a massive, stocky rhinoceros. He is dull blue in color, with two lighter spots and one darker spot on his cheek. Some spots (both lighter and darker) can also be found on his back. He has dark eartips with a pink inner ear and two white horns, the front significantly larger than the other. His eyes are pure black.
Mbeya is very loquacious, friendly, polite, talkative, magniloquent, communicative, unreserved, and chatty. He is also claimed to know the Pride Lands "like the back of his horn".
However, he can also be very stubborn, and quick in leaping to conclusions. But he is not above admitting when he is in the wrong, and issuing apologies where needed.
After Kion is swept across a river into the Outlands, he instructs the rest of the Guard to meet him at Flat Ridge Rock. As a result, the Guard seeks out information from Mbeya, after a suggestion from Beshte. He and Beshte talk for a while, but the Lion Guard become impatient, insisting that Beshte stops his conversation so that they can rescue Kion. Beshte recalls that he never did ask Mbeya where Flat Ridge Rock was as they were too busy discussing a recent heat wave, and goes back to Mbeya do so.
On the day of Kupatana, Mbeya winds up stuck in the mud at Lake Matope. The Lion Guard rescues him, and Mbeya is seen thanking them and receiving reassurance from Kion, whilst Ono hopes that next time he won't get stuck in mud that is quite so sticky.
Mbeya and several other leaders are chosen to take part in Simba's Savannah Summit. Whilst concerned at Makuu's inclusion, he proceeds regardless. Mbeya is at first grouchy, going so far as to fling Big Baboon away from him when he tries to settle on his head on the way to Mizimu Grove. But after Simba calms the group down, he starts to soften a bit.
Later, Mbeya and Big Baboon have their portrait painted by Rafiki, who urges Mbeya to stand so that he can finish. While the stubborn rhino refuses, the Lion Guard arrive, having heard a distressed cry from Zazu. Rafiki then guides them to the hornbill, who is trapped underneath Mbeya's backside. Mbeya refuses to move until he gets an apology from him. Zazu is confused, so Mbeya explains to the Lion Guard that he called him clumsy. But Big Baboon reveals that it was actually he who called him clumsy, since he bumped into him. Mbeya finally releases Zazu, just in time for Big Baboon to mock him. But the baboon soon apologises, which Mbeya accepts. He then apologises to Zazu for sitting on him.
At sunset, he hears from Kion that Makuu passed away after falling into a trap. Despite his lack of trust towards the croc, he is saddened by the news. But when Twiga and Vuruga Vuruga confess that it was they who created the pit as a trap, he is shocked at their actions. He is shocked further when Makuu appears, having heard everything. When Makuu announces that it was a plan worthy of him and that the summit can go on, Mbeya cheers with everyone.