The last lion to lead a Lion Guard in the Pride Lands was Scar, Mufasa's younger brother, who abused his power by using the Roar of the Elders for evil. When Kion, Kiara's younger brother, was born, he would be the next to lead a Lion Guard. When he was a cub, he first used the Roar of the Elders to defend his friend Bunga from hyenas. This was how it was confirmed he would indeed lead a Lion Guard.
Kion's father Simba tasked him with finding suitable members for his group. Eventually he did: Bunga, the bravest, a honey badger, Fuli, the fastest, a cheetah, Beshte, the strongest, a hippo, and Ono, the keenest of sight, an egret. However, when Simba found out that Kion had chosen non-lions for the Lion Guard, he scolded his son and told him to find other members.
Disheartened, Kion went to have some alone time, and there he encountered his grandfather Mufasa through the heavens. Mufasa encouraged Kion and told him he would always be there for him. Mufasa's wise advice would help Kion throughout the following years.
Kion gathered his team again and gave them all the Mark of the Guard. They defended the Pride Lands from an attack by Janja the hyena and his clan. Simba realized he was wrong and congratulates his son on the victory, now knowing Kion was right in those he chose for the Guard.
Throughout the next few years, Kion and his team defended the Circle of Life against many threats, made new friends, and protected countless animals. When Kion received a scar in battle with snake venom inside, him and his team had to make a long journey to the Tree of Life, where Kion and Ono, who was also injured, could receive healing. Kion created the position of the smartest for Ono to fill, while Anga, a martial eagle, took his place as the keenest of sight.
After a long journey, the Guard was attacked by the Night Pride, who defend the Tree of Life. After some explaining, both groups reconciled, and the Night Pride led them to the Tree of Life.
Kion's healing process took longer than he wanted. While at the Tree of Life, they met new animals and defended the Tree from attacks by Makucha's army, a villain the Guard had recently dealt with.
Kion and Rani, the princess and later queen of the Tree of Life, began to fall in love as Kion's visit prolonged. Right after they confessed their love and Rani proposed to Kion, the Lion Guard informed their leader they were ready to go home. Kion and Rani bid farewell, while Makini, Rafiki's apprentice who had accompanied the Guard, stayed behind, having found her place as an advisor to Rani.
Kion and his Guard, accompanied now by a reformed Janja, Jasiri and Azaad - Fuli's love interest - made the journey back home. They were surprised to find out that all was well in the Pride Lands, as the two hyenas had come to warn the Guard of Zira's attacks on Simba's pride. Upon entering the Pride Lands again, the Guard was met with yet another surprise - Vitani, Zira's daughter, had formed her own Lion Guard while Kion was away.
After much bickering (and explaining of the recent events from Kovu and Kiara), Vitani and Kion's Lion Guards held a competition to see which group had the right to protect the Pride Lands. In the end, Kion forfeited and gave Vitani the Roar and leadership of the Lion Guard, once she proved to be the fiercer lion. Kion and his Guard then went back to the Tree of Life and joined the Night Pride. Kion married Rani, and Fuli and Azaad became mates.
When Kovu and Kiara had children, Vitani authorized a mini Lion Guard for their second-born son, Kheri, to lead.
