When she was young, a sage told her a "mantra" with which Kunti could summon any god and have a child by him. When Kunti asked why he gave her this mantra, he told her that it would be useful to her later in life.
Kunti could not believe the mantra, so she tried to use it. The Sun God, Surya, appeared. She asked him to go back, but Surya said he was compelled to fulfill the mantra before returning. Surya magically caused Kunti to bear a child immediately so that she, a princess, would not be subject to questions from the King or his court. Kunti then discarded the child, Karna, in a basket in a river. Karna was later found by a charioteer of Kunti's future brother-in-law. The ambiguous emotions Karna felt about Kunti play an important role in the Mahabharata.
Later on, Kunti married Prince Pandu of Hastinapur. Pandu had a blind elder brother, Dhritrashtra. When Pandu's father died, Pandu, and not Dhrithrashtra, became King. According to the laws of the time, a blind man could not rule unless he was the only heir to the dead king. Thus Pandu, a younger son, came to the throne. Pandu, as was the custom of the time, took a second wife, Madri.
One day, Pandu, Madri, and Kunti were hunting for sport in a forest. Pandu used a magical arrow intended to kill a stag. The arrow would mystically strike whatever the shooter last heard before releasing the arrow. As Pandu was preparing to use the arrow, he heard the stag's roar, so he let go of the arrow. But before the arrow actually left the bow, Pandu heard the voice of a man.
Pandu could not stop the arrow, which struck the man and killed him. Before dying, the man, who was on his way to his wife, cursed Pandu that the latter would die the moment he touched his wife.
Pandu, grief-stricken that he could not have any children, abdicated the throne and left in self-imposed exile. While in the forest, Pandu yearned for the children he could not have. Then, Kunti revealed her secret mantra. She used it thrice, first receiving a son Yudishtira from god Yama, next for Bhima from god Vayu, and third for Arjuna, from god Indra. Kunti revealed the mantra to Madri, who bore two twin sons, Nakula and Sahadeva, from the twin gods the Asvins. The five together are known as "Pandavas".
One day, Pandu could not control himself and touched Madri. Immediately, he burnt to ashes. Madri, feeling herself responsible, immolated herself. Kunti was left to tend for all five sons, whose story forms an integral part of the Mahabharata.