- “It is time.”
At sunrise in Tanzania, Simba is teaching Kiara how to be Queen of the Pride Lands when her little brother Kion and his honey badger friend Bunga interrupt them. After apologizing, the boys take their game elsewhere: the Savannah. Suddenly, their ball is knocked into the Outlands. Kion doesn't want to go in because his father said not to, but Bunga goes in, anyway. Unfortunately, he bumps into the Hyena Clan led by Janja. Kion saves him with a very powerful roar. After making the roar, a mark shaped like a lion appears on his fur.
Back at Pride Rock, it's revealed that Simba, Nala, and Rafiki heard the roar. Despite Simba's reservations, Rafiki declares Kion ready for his destiny. Rafiki tells Kion his roar is the Roar of the Elders and Simba tells him it means he's destined to be the leader of the new Lion Guard. He takes Kion to the cave and gives him the history of the Lion Guard: It's composed of the bravest, strongest, fastest, fiercest, and keenest of sight in the Pride Lands to protect the Pride Lands. He also tells his son that the old Lion Guard's end was not happy: When Mufasa was heir to the throne, Scar was head of the Lion Guard due to having the gift of the Roar. However, Scar let the power go to his head and lead to him to desire to become King. After he failed to convince the Lion Guard to help him take down Mufasa, he used the Roar to destroy the old Lion Guard. However, for using the Roar for evil, Scar lost the Roar forever. Rafiki tells Kion that the Roar can be used for great good but can lead to terrible evil. Kion vows that he will never be like Scar and begins devoting himself to the task of assembling a new Lion Guard. He picks Bunga as its first member since he's the bravest animal he knows. However, they are overheard by a vulture named Mzingo who flies off to tell Janja.
Meanwhile, Kion and Bunga help Kiara's friend Zuri get unstuck and meet up with Timon and Pumbaa. Kion tells them about the new Lion Guard. Bunga tells them it gonna live by the philosophy of Zuka Zama. He gives a musical explanation of what that is. Kion and Bunga then leave to assemble the rest of the Lion Guard. A jealous Kiara heads back to Pride Rock to inform Simba of this.
Meanwhile in the Outlands, Mzingo tells Janja what Kion is doing. Janja decides a new Lion Guard will be trouble for Outlanders and decides to launch a pre-empitive strike. Meanwhile, Kion recruits Ono, Beshte, and Fuli to be part of the Lion Guard. He then tries to show them the Roar of the Elders but all that comes out is a squeak. Immediately afterwards, Simba comes by and tells Kion that the Lion Guard has always been made up of lions and that it's not a game he plays with his friends and that he needs his son to take his new responsibilities seriously like Kiara does with hers.
Meanwhile, Kiara and her other friend Tiifu are tracking a gazelle herd. However, upon noticing, Janja and his clan going into the herd, Kiara sends Tiifu to fetch Simba. Soon enough, the hyenas cause a stampede among the herd, Kiara becomes trapped in it whilst Tiifu, Simba and Nala watch on in horror. Elsewhere, Kion is feeling discouraged because of what his father said. The spirit of Mufasa appears and encourages him to trust his instincts. Kion finds new inspiration in his grandfather's words. After learning about the Hyenas' attack, he comes up with an idea to stop them. Together, the new Lion Guard defeats the hyenas. Then, Bunga saves Kiara with a Pumbaa worthy fart. Kion then sends the hyenas packing with the Roar, with Janja vowing to Kion that he and his Lion Guard haven't seen the last of him. This makes Simba realize that Kion knew what he was doing when he chose his friends to be part of the new Lion Guard and that he is indeed ready.
- Kion (Max Charles) - The protagonist, Simba and Nala's son, Kiara's younger brother and Prince of the Pride Lands. He is the leader and fiercest member of The Lion Guard.
- Simba (Rob Lowe) - Nala's mate, Kion and Kiara's father and King of the Pride Lands.
- Nala (Gabrielle Union) - Simba's mate, Kion and Kiara's mother and Queen of the Pride Lands.
- Kiara (Eden Riegel) - Simba and Nala's daughter, Kion's older sister and Princess of the Pride Lands.
- Rafiki (Khary Payton) - a mandrill who serves as shaman to the Pride Lands.
- Timon (Kevin Schon) - Simba's meerkat friend and Bunga's adoptive uncle.
- Pumbaa (Ernie Sabella) - Simba's warthog friend and Bunga's adoptive uncle.
- Mufasa (James Earl Jones) - Simba's father and Kion and Kiara's paternal grandfather who died in the first film.
- Bunga (Joshua Rush) - Kion's honey badger friend and Timon and Pumbaa's adoptive nephew. He is the bravest member of The Lion Guard.
- Fuli (Diamond White) - Kion's cheetah friend. She is the fastest and only female member of The Lion Guard.
- Beshte (Dusan Brown) - Kion's hippo friend. He is the strongest member of The Lion Guard.
- Ono (Atticus Shaffer) - Kion's egret friend. He is the keenest of sight in The Lion Guard.
- Tiifu (Sarah Hyland) - A Pridelander cub and a friend of Kiara's.
- Zuri (Madison Pettis) - A Pridelander cub and a friend of Kiara's.
- Janja (Andrew Kishino) - The teenage leader of the hyenas who live in the Outlands.
- Mzingo (Greg Ellis) - A hungry Rüppell's griffon vulture and Janja's majordomo
- Cheezi (Vargus Mason) - A crazy hyena and a member of Janja's clan.
- Chungu (Kevin Schon) - A touchy hyena and a member of Janja's clan.
- The Lion Guard: Return of the Roar on Wikipedia
- The Lion Guard: Return of the Roar at The Big Cartoon DataBase
- Judging by Kiara's age, the film takes place during the first act events of The Lion King II: Simba's Pride, during Kiara's childhood.
- Right after Kion sings the line "...the lion I was born to be" in his song, he leaps and you can see his soon-to-appear Lion Guard mark on his inner right thigh.
- While Kion is inducting Fuli, he says, "You are the fastest," but watch his lips - they don't match up to what he's saying.