Mamoudou Kouyaté, a griot and the narrator, says that griots are the vessels of speech and the keepers of history who teach kings their history so they can predict the future. Mamoudou Kouyaté asks the reader to listen to the history of Mali and of Sundiata. At first, Mali was ruled by Bambara kings, and Mamoudou Kouyaté lists the lineage of these kings down to Sundiata's father, Maghan Kon Fatta.
Maghan Kon Fatta spends his time sitting under the great silk-cotton tree in Niani, and his first son, Dankaran Touman, sits with him. One day, a hunter approaches Niani with an offering for the king. Maghan's griot, Gnankouman Doua, invites the hunter to sit with them. The hunter is a soothsayer, and as he jumbles his cowrie shells, he tells Maghan that the silk-cotton tree grows from a tiny seed. He says that if Maghan marries the ugly woman currently heading for Niani, she will bear his successor and this successor will be greater than Alexander the Great.
The brothers Oulamba and Oulani arrive at Niani with a woman between them. They offer her to Maghan as a gift, and tell the tale of how they won her hand by killing the Buffalo of Do. Maghan agrees to marry the woman, Sogolon. On their wedding night, Sogolon refuses her husband's sexual advances. A week later, Maghan tricks Sogolon and impregnates her while she has fainted.
Sogolon, now pregnant, moves freely through the king's enclosure, but Maghan's first wife, Sassouma, is jealous and tries to kill Sogolon. Sorcerers refuse to kill Sogolon, and Sogolon goes into labor. She gives birth to a boy, whom the king names Mari Djata.
By the age of three, Mari Djata still doesn't walk, but he habitually hits his playmates with his strong arms. Sassouma is thrilled about the boy’s incapacity. Sogolon has a girl and Maghan takes a third wife, Namandjé, who gives birth to a boy, Manding Bory. Soothsayers indicate that Manding Bory will be the right hand man of a king. Maghan consults a soothsayer who indicates that the "seed" has germinated, but man is simply impatient. All of Niani continues to gossip about Mari Djata, but Maghan bestows upon the seven-year-old boy his own griot, Balla Fasséké. Maghan and Gnankouman Doua die not long after, and Sassouma ensures that Dankaran Touman is crowned king against his father's wishes.
Sassouma banishes Sogolon and her children to a hut behind the palace, where Sogolon plants a garden. One day she finds she's out of baobab leaf and asks Sassouma for some. Sassouma gives her the condiment but insults Sogolon and Mari Djata. Back at her hut, Sogolon hits Mari Djata and asks him if he'll ever walk. Mari Djata calmly asks for an iron rod and declares he'll walk today. He asks his mother if she'd like only the baobab leaves or the entire tree, and Sogolon asks for the entire tree. Balla Fasséké fetches a sturdy iron rod from the smith and offers it to Mari Djata. The boy lifts the bar vertically and draws himself to a standing position, twisting the bar into the shape of a bow in the process. Balla Fasséké composes the song “Hymn to the Bow,” and Mari Djata takes giant steps. He uproots a baobab tree and throws it at his mother's doorstep.
By age ten, Mari Djata becomes known as Sundiata. He's very popular amongst his peers, and fearing this popularity, Sassouma assembles nine witches and asks them to kill Sundiata. The witches make a show of "stealing" from Sogolon's garden to provoke Sundiata, but Sundiata generously offers them vegetables and meat. The witches, astounded by his kindness, offer to protect the boy.
Sogolon suggests that she and her children leave Niani, as she knows that Sassouma will now turn to hurting Manding Bory and Sundiata's sisters. Sundiata agrees and Balla Fasséké plans for the journey, but Dankaran Touman sends Balla to Sosso to speak with the king Soumaoro Kanté, effectively robbing Sundiata of his griot. When Sundiata returns and realizes what's happened he confronts his brother and vows to return to Mali. Dankaran Touman is shaken, but at his mother's prodding, he decides that if he sees Sundiata and Manding Bory again he'll kill them.
Sogolon and her children travel to Djaba. They stay for two months until the king, Mansa Konkon, calls Sundiata to him to play a game of wori. Mansa Konkon stipulates that if Sundiata loses, Mansa Konkon will kill him. Sundiata realizes that Sassouma has bribed Mansa Konkon, and Sundiata and his family leave the next day. They wind their way through the country and end up in Wagadou, Ghana. The king of Ghana welcomes Sogolon and her children. Sundiata and Manding Bory are treated like royalty and Sundiata accepts this treatment. When Sogolon falls ill a year later, the king of Ghana sends the family to Mema. Moussa Tounkara accepts Sogolon and Sundiata and takes Sundiata on his first military campaign. When Sundiata performs well, the king vows to make Sundiata a great warrior. When Sundiata is 18, Sogolon reminds Sundiata that his destiny lies in Mali.
The narrator describes Soumaoro Kanté, the evil sorcerer king of Sosso. Soumaoro keeps Balla Fasséké at his court and threatens Dankaran Touman if he doesn't submit to Sosso. Dankaran Touman sends his sister Nana Triban to Soumaoro and submits. One day, Balla Fasséké sneaks into Soumaoro's secret chamber of fetish objects. Balla finds a massive balafon (musical instrument) and sits down to play. Soumaoro knows that someone is playing his balafon and he bursts into the room, but Balla improvises a song in honor of the king. Soumaoro decides to keep Balla for himself, which the narrator says made war inevitable between Soumaoro and Sundiata. Soumaoro, emboldened by his power, abducts the wife of his nephew Fakoli. Fakoli, angry, revolts against his uncle. Malian kingdoms try to help Fakoli, but Soumaoro burns their cities, including Niani, to the ground. A group of soothsayers form a resistance group and set out to find Sundiata.
One day, Sundiata's sister, Kolonkan, is in the market of Mema buying vegetables and she finds a merchant selling condiments from Mali. The merchant is interested in Kolonkan and her brother, and asks if Sogolon would speak with them. Kolonkan runs home to ask Sogolon, and Sogolon agrees to see the merchants. When the merchants arrive at Sogolon's quarters, she recognizes them as members of her husband's court. They share the grave news from Mali. Upon hearing the news, Sundiata decides to speak with Moussa Tounkara about returning to Mali. The next day, Sogolon dies. Sundiata approaches Moussa Tounkara, explains that he must return to Mali, and asks to bury Sogolon in Mema. Moussa Tounkara tries to refuse, but an advisor encourages him to grant Sundiata his requests. Moussa Tounkara sends Sundiata with half of his army.
Sundiata heads for Tabon, but finds that Soumaoro's forces, led by Sosso Balla, are blocking the way. Sundiata's forces attack Soumaoro's immediately and win. Sundiata's childhood friend Fran Kamara, now known as Tabon Wana, king of Tabon, rides out to meet Sundiata. They join forces and, not long afterwards, Soumaoro attacks Tabon. Sundiata's army is successful, but when Sundiata tries to throw a spear at Soumaoro, it bounces off his chest and Soumaoro simply disappears. While Sundiata was technically victorious, he spends his night wondering how to beat Soumaoro's magic.
Sundiata continues recruiting troops, and they all gather at Sibi with Kamandjan, the king of Sibi. Sundiata pledges to take back Mali. He consults soothsayers about Soumaoro's magic, and they advise Sundiata to make animal sacrifices. During the butchering, Sundiata hears that Nana Triban and Balla Fasséké managed to escape Soumaoro. He goes to them, and they explain how they escaped. Nana Triban tells Sundiata how to pierce Soumaoro's magic. Before the great battle, Sundiata's war chiefs perform fantastical feats and pledge allegiance to Sundiata.
Soumaoro and Sundiata properly declare war on each other. Fakoli joins Sundiata's cause and is accepted by the war chiefs. On the day of the battle, Sundiata carries an arrow made of wood and tipped with the spur of a white cock. Balla Fasséké shares that he saw the end of Soumaoro in a dream. As the battle rages, Sundiata shoots the arrow at Soumaoro. Soumaoro feels his powers leave him and turns to retreat. Sundiata and Fakoli chase him. They stop in several villages along the way and learn that Soumaoro is accompanied by Sosso Balla. Sundiata and Fakoli finally catch up to the runaways in the mountains. They capture Sosso Balla, but Soumaoro escapes into a cave.
The following morning, Sundiata attacks Sosso and burns it to the ground. He proceeds to then take the cities of Diaghan and Kita. The king of Kita is protected by the power of an evil jinn, whose powers are concentrated in a pool in the middle of a mountain. After Kita submits to Sundiata, Sundiata decides to travel to the pool and thank the jinn for his victory. Sundiata drinks from the pool and when he returns to his army, he looks exceptionally brilliant. Sundiata and his army travel through Do. When they see a whirlwind, Balla Fasséké says it's time to return to Mali.
Sundiata gathers his forces at Ka-ba. All the kings pledge allegiance to Sundiata, and the sofas perform their war dances. Sundiata creates alliances between his kingdoms and officially grants the kings their new kingdoms. He proclaims Balla Fasséké grand master of ceremonies. Sundiata remains in Ka-ba for several days and then begins the journey to Niani. He finds the city sad and burnt, but he restores it to be larger and more glorious than before. In the new empire, Manding Bory acts as Sundiata's viceroy. Sundiata holds a yearly assembly of kings and dignitaries at Niani, and this assembly allows Sundiata to maintain control and justice. Mali flourishes under Sundiata's rule.
Mamoudou Kouyaté says that many kings ruled after Sundiata, but none were as great as Sundiata. He implores the reader to go to Mali and see the old cities, but cautions that one can't go to the dead cities and question the past. He states where Sundiata is buried, and explains that he himself acquired his knowledge and this story by traveling around Mali.