Peng was rumored to have haled from a valley over from the Valley of Peace, where he spent much of his life learning pottery from his family. At some point in his life, however, he grew more interested in Kung Fu and became a big fan of it, but since he had no formal training, he eventually leaned the martial art for himself. By the time he was a teenager, Peng left his hometown in search of members of his family who were separated from his mother or father as infants, including his uncle Tai Lung, though it was unknown of how much he knows of his uncle or if he was aware of his atrocity against the Valley of Peace.
When Peng arrived in the Valley of Peace, he signed himself up to partake in the Peace Jubilee. Someone proposed that he should fight Jing Mei, the nephew of Temutai, who was one of the masters hosting the celebration. Peng was at first hesitant until Jing Mei knocked down his pottery cart, and agreed to the fight. He introduced himself to Master Shifu and assure the Dragon Warrior, Po, that he wanted to fight. When the match began, Peng first evaded Jing Mei's attacks but then countered one and finished the fight with three airborne spin-kicks, easily winning the match. But before he could take his leave, both Po and Temutai tried to convince him almost turning into a fight until Shifu declared it was Peng's choice. The young snow leopard decided to train with Po at the Jade Palace, but on their way there, he was mobbed by a group of children who became his new fans and signed autographs before at last he was taken to the Training Hall. There, he met and was complimented by the Furious Five, who offered him a run through the training course, which he traversed in seconds flat. At dinner, Peng sat at the head of the table (where Po was supposed to be sitting as host) and told some jokes, succeeding in making Tigress laugh.
Later, he met up with Po in the Training Hall again, where the Dragon Warrior haltingly told Peng that Shifu had dismissed the young potter's skills as a warrior. This outraged Peng, who declared he'd prove Shifu wrong before running off. He sought out Temutai and told him what happened before picking up a sword, proclaiming he would defeat the Qidan Clan leader and show Shifu what real strength was. The fight continued outside and before long, everyone (the Furious Five, the Qidan Warriors, and the villagers) were all fighting and squabbling until Po shouted for everyone to stop. It was there that the panda confessed that it was he who wanted Peng gone, not Shifu, because he got jealous of the leopard cub's popularity, and sincerely apologized. Though shaken, Peng found it in his heart to forgive Po, and partook in the closing ceremony with Po and Temutai by performing tai chi. When the Jubilee was over, Po invited Peng back to the Jade Palace, but Peng politely declined as he wanted to continue his travels, giving an example of his objectives out of his search for his uncle. When Po asked what Peng knew about his uncle, the young leopard answered that whoever his family left his uncle to be adopted by named him "Tai Lung", giving his new panda friend a shock.
During his ongoing travel, the friends Peng met along the way told him stories about Tai Lung, though he only heard them ending them with the fact that his uncle was defeated and destroyed by the Dragon Warrior. Outraged by disbelief, Peng returned to the Valley of Peace and was found by Po, Crane and Monkey fighting a couple of Croc Bandits. Po, after telling Monkey and Crane about Peng's connection with Tai Lung, tried to avoid being seen by the leopard cub as the latter was brought up to the Jade Palace to ask Shifu if he could see him, even by disguising himself as Zeng via a shift stone, but got his cover blown when the real Zeng burst in and reported the stone's disappearance, prompting Shifu to take the it from the panda and revert him back into his actual form. When Po admitted that the story was true during their walk in a bamboo forest, Peng was angry and tried to attack him, kicking him off a cliff into a river when the panda accidentally tried to use the Wuxi Finger Hold on him the same way he did on the snw leopard cub's uncle. However, Peng returned to the Jade Palace and realized that Po was right about everything, now believing Kung Fu as something like poison and quitted it by leaving behind his uncle's old sword.
Peng returns once more as he and his girlfriend Lin Fa have started an illegal fight club to teach the average person kung fu to protect themselves. When an ox challenges and defeats everyone while calling them losers, Lin fa tells him that at the club everyone treats each other with respect and Peng proceeds to kick the ox out. Later, Po manages to sneak into the club and ends up accidentally revealing his identity when the bucket concealing his face falls off after he is punched in the stomach. Po says that while the club is cool he has no choice but to shut the club down, but Peng (masked) says he won't allow that. Peng comes onto stage to fight Po, and while Po manages to defend himself, when Peng reveals his identity, distracting Po long enough for Peng to kick him unconscious. Po wakes up hours later and yells furry treachery before Peng stops him and explains that he decided kung fu wasn't the cause of corruption but the fact that the masters monopolized it and refused to share its secrets with others, leaving them vulnerable. While Peng believes Po will shut the club down, Po instead eagerly decides to join the club, much to Peng and Lin Fa's happiness and the next week he helps train the new recruits, with Peng stating it has been the greatest week of his life. Po then suggests they reveal themselves to the town to spread the word, something Peng and Lin Fa like while Po distracts Shifu from coming. Soon, Tong Fo learns of the club and finds them. He ties them both and threatens to kill Lin Fa if Peng doesn't kill Po. He even tells Peng that since he is Tai Lung's nephew he is bound to become bad like him and he should stop fighting him. Peng fights Po as promised but reveals to Po during the match that Lin Fa will be killed if he doesn't kill Po and that Po shouldn't have trusted him. Po says he knows Peng is good before Peng stings him with the needle laced with deadly poison. He confronts Tong fo, and then reveals they faked Po's death and begin attacking Tong Fo. Peng corners Tong Fo who orders Lin Fa to be killed but Lin Fa has managed to free herself and orders a free fight against Tong Fo's men. Peng manages to get payback for what Tong Fo did to Lin Fa and Shifu reveals he has been watching and enjoyed the fight club and decides to sanction the kung fu club as legal, much to Peng, Po and Lin Fa's happiness. Peng and Lin fa leave to establish more fight clubs and Po bids them farewell.
Peng is shown to be modest and rather humble for someone so skilled, as he didn't actually want to fight until Jing Mei forced his paw. Even so, Peng showed a sense of determination that reflected that of his uncle, in that while he may not seek out fights, he will do whatever it takes to finish them on his own terms.
Being young, he understandably got excited by the opportunity to train in the Jade Palace with Shifu, the Furious Five, and Po, but he seemed to share Tai Lung's ambition in proving himself, shown when he recklessly sought to defeat Temutai to prove himself worthy. He claimed he had practiced his kung fu without expectations and no dreams until Po gave him one, hinting he might be self-taught and had done so with great effort. This also implies that he is similar to Tai Lung, in the respect how Tai Lung was filled with hopes of being dragon Warrior only to have the title not given to him, resulting in the darkness of his heart emerging and harming people. He even attacked Po when he found out he killed his uncle, though stopped after learning Tai Lung was evil. Throughout his appearances, Peng struggles between doing what is right and the belief that he will follow Tai Lung's descent to darkness as his nephew which is something he fears the most, but Po is always there to remind him that he is nothing like Tai Lung and is truly a good person at heart.
Even so, Peng was shown to be far more forgiving than Tai Lung was, as he forgave Po for lying to him and hurting his feelings and pride. It is possible that Peng possesses all the positive aspects Tai Lung himself once had when he was his nephew's age.
He also fears of being evil, so to avoid this from happening, he quit kung fu. However, after meeting Lin Fa, he decides that it wasn't kung fu that was corrupt but the manner in which it was kept secret from the public with only the masters at sanctioned palaces being able to practice it, showing what appeared to be bitterness at the hierarchy ad power struggle that came with it as he seemed to being to resent the poewr the palace held. However, after Po found out about his illegal fight club (since amateur kung fu is banned) and showed he wholeheartedly supported it, Po seemed to improve in his vision. He eventually sees this as his true purpose and states he has never been happier, especially with Lin Fa at his side and he may have finally found inner peace both with his identity as Tai Lung's nephew and the fact that he was nothing like his uncle.