He is voiced by Danny Cooksey.
It was briefly mentioned that Peng is from "the valley over" from the Valley of Peace, where he was presumably raised by his family and learned pottery. It is unknown, however, when Peng started training in kung fu, though he admitted at one point to have no formal training, hinting that he is self-taught.
When he became a teenager, Peng left his hometown in search of his uncle Tai Lung, though it is unknown how much he knows of his uncle. He stopped in the Valley of Peace to partake in the Peace Jubilee, where he would be discovered as a kung fu prodigy by the master of the Jade Palace.
In Legends of Awesomeness
In "The Kung Fu Kid", Peng arrived in the Valley of Peace to partake in the Peace Jubilee. Upon his arrival, someone proposed that Peng fight Jing-Mei, the nephew of Temutai, who was one of the masters hosting the celebration. Peng was hesitant until Jing-Mei knocked down his pottery cart, and agreed to the fight. He introduced himself to Master Shifu and assured the Dragon Warrior 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. Before he could take his leave, both Po and Temutai tried to convince Peng to train with one of them, 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.
On their way to the Palace, Peng was mobbed by a group of children who had become his new fans and signed autographs before at last he was taken to the Training Hall where he met and was complimented by the Furious Five, who offered him a run through the training course. Peng traversed it 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 is.
During their fight, Peng got Temutai on the defensive when they were interrupted by Jing-Mei. Not wanting to get involved he quickly excused himself, much to his uncle's fury. Finally, Po showed up and tried to stop the fight; but Peng refused to back down, exclaiming he "practiced his kung fu without any plans, no expectations, and no dreams" until Po "gave him one" and Shifu "snatched it away".
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. Here, Peng got a confession from Po that he was the one who wanted Peng gone, not Shifu, because he got jealous of Peng'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, revealing that he was searching for his uncle. When Po asked who his uncle was, he received a shock when the young snow leopard revealed that his uncle is Tai Lung.
In "Master and the Panda", Peng returned to the Valley of Peace to speak to Po after finding out about his uncle. When Po revealed the truth Peng was angry and tried to attack Po, believing that Tai Lung wasn't evil. However, Peng returned to the Jade Palace and realized that Po was right about everything and that kung fu causes evil. Peng quit kung fu and left behind his uncle's sword.
When Temutai attacked the Jade Palace wearing the Gong Lu Medallion, Po sought out Peng's help and convinced him that he wouldn't turn out evil. They defeated Temutai as a team and knocked the medallion off him. However, Peng picked up the medallion and the power corrupted him. He started to attack the Five and then Po, causing them to roll down the stairs (similar to the fight in the first film).
Peng knocked Po aside, wishing his uncle was still around to see his victory. Tai Lung then appeared from the shadows, stating that he was a manifestation from the medallion. Tai Lung instructed Peng to destroy everything, including the innocent, but before Tai Lung could hurt anyone, Peng stopped him, stating that he was nothing like Tai Lung and took the medallion off himself. Tai Lung then transformed into Po (who used a shifting stone to change his appearance). Po told Peng that despite having a dark side, he was able to stop before he went too far.
However, Peng still believed that he holds some of the same evil that corrupted Tai Lung and left the Jade Palace, vowing to never do kung fu again.
In "Kung Fu Club" 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 the 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's 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 of how Tai Lung was filled with hopes of being a 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 being evil, so to avoid this from happening, he quit kung fu. However, after meeting Lian, 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 be to resent the power 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 Lian 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.
Peng is shown to be a kung fu prodigy, though he claims he has had no formal training or instruction. He fights with a level of skill very similar to that of his uncle's—enough to force a kung fu warrior like Temutai on the defensive, traverse the Training Hall in almost seconds flat, and show some skill in swordsmanship. He fights by evading, turning his opponents' strength against them, and uses aerial kicks when on the offensive.