Mbeya is a massive, stocky rhinoceros. He is dull bluish-gray 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.
Mbeya hears about the Traveling Baboon Show, and waits around a sausage tree for their performance to start. He is amused when Uroho, the leader, makes a joke about his horn just before the beginning. After the show he leaves, but joins a group to watch a second showing.
Afterwards, he and a group of animals notice that all of the food in one area has vanished. The Lion Guard are called over, but when Mbeya tries to talk, Thurston interrupts him. The Lion Guard agree to investigate, and Mbeya leaves, and watches another baboon show while he waits.
Later, he waits in line for Uroho to hand him a free piece of fruit with the offer of another show.
When Tsetse Flies invade the Pride Lands, they eventually make their way over to Mbeya. When the Lion Guard find him, they see that he is completely overturned in a small ditch. After Beshte helps him get out, Mbeya explains how he was rolling around to get rid of the flies, but accidentally rolled into the stream bed by mistake. The Lion Guard offer to escort him to a watering hole, but notice Thurston's Herd waiting nearby. When the flies disappear, Ono comes to the conclusion that it's the zebra stripes that they don't like. The Lion Guard escort both the herd and Mbeya to a new watering hole, their journey uninterrupted by the flies.
When Bunga wants to give his uncles the best Christmas ever, Mbeya agrees to join in with the celebrations. After rehearsing all night, they are about to give up until Bunga reveals to them how important it is to him, and why.