Uttarā (Uttara) was the daughter born of the womb of queen Sudeṣṇā (Sudeshna), and sired by king Virāṭ (Virat) of the Matsya kingdom.
In Virāṭparva (Viratparva) of Mahābhārata (mahabharata0, when the Pāṇḍava(s) were spending their Ajñātavāsa in the royal house of Virāṭ, Arjuna disguised as Vṛhannalā (Vrihannala), a eunuch, came in front of the king, and said, I am well-versed in the arts of singing, dancing and playing instruments. You can entrust to me the responsibility of your daughter Uttarā–
tvamuttarāyai paridatsva māṃ svayaṃ bhavāmi devyā naradevānartakaḥ.

King Virāṭ appointed Vṛhannalā as the dance and music teacher of Uttarā and the other girls of her age. Uttarā took lessons fro Vṛhannalā, and so she loved and respected him as a teacher and a father-figure. Arjuna was also very affectionate towards her, and and he used to satisfy all her fond entreaties. At the end of Ajñātavāsa, Arjuna himself speaks of his close relation with Uttarā–
antaḥpure’muṣitaḥ sadāpaśyaṃ sutā tabva
rahasyañca prakāśañca viśvastā pitṛvanmayi.
priyo vahumataścāsaṃ nartako gītakovidaḥ
ācāryavaccamāṃ nityaṃ manyate duhitā tava.
How much affectionate Arjuna was towards Uttarā, becomes clear from the words of Draupadī, in the Goharaṇa (stealing of cows) episode, immediately before the Virāṭ-battle. When the prince Uttara was boasting– “if I had a good charioteer, I would have defeated the Kuru army and rescue the cows”– Draupadī suggested, “You should request Vṛhannalā through Uttarā, to become your chariot-driver. He won’t be able to deny Uttarā’s request–
yeyaṃ kumārī suśroṇī bhaginī te yavīyasī
asyāḥ sa vīro vacanaṃ kariṣyati na saṃśayaḥ.
Truly, Arjuna could not deny Uttarā’s request. Uttarā herself knew that Vṛhannalā had a great affection for her, so, along with conveying the request, she added — if you don’t keep this request of mine, I’ll give away my life.
athaitavacanaṃ me’dya niyuktā na kariṣyasi
praṇayāducyamānā tvaṃ parityakṣāmi jīvitam.

However, finally at the request of Uttarā, Vṛhannalā set off to battle, as the charioteer of Uttra. Before the journey Uttarā further asked him to bring the clothes of the Kuru warriors, for the decoration of her dolls. Arjuna kept that request, too.

In this episode of Mahābhārata, there is a brief description of Uttarā’s beauty. In the text maintained by Haridāsa Siddhāntavāgiśa, this portion is absent. From this description, it appears that Uttarā was a girl of extraordinary beauty.

At the end of Ajñātavāsa, king Virāṭ expressed his wish to get Uttarā married to Arjuna. But Arjuna accepted her as his daughter-in-law. He said, “For the last one year, myself and Uttarā have stayed together. Uttarā trusted me as a father-figure, and I have also treated her as my daughter and disciple. Now, if I marry her, people would say, I was attracted to her. They would raise question about both her character, and mine.” It was also known to all that Arjuna was much fondly attached to Uttarā. So, what Arjuna said, was not without a base. In fact, seeing Arjuna’s affection towards Uttarā, it was not impossible that the other Pāṇḍava9s) or Draupadī might think of such things. Especially Uttarā was young and one of unmatchable beauty. Uttarā, a kṣatriya girl, could also be attracted towards a handsome hero like Arjuna. After the slaying of Kīcaka, Draupadī said to Arjuna, in a taunting tone– “You are quite well as a dancer in this women’s quarter”– this could have been true, if Arjuna agreed to marry Uttarā. Instead, the way Arjuna has referred to their relationship as one between parent-child, comes as a fitting reply to all these doubts. After this, the way Arjuna mentions the qualities and prowess of his son Abhimanyu, and arranges his marriage with Uttarā, it seems that since the last year, he has actually been looking for such a girl as his daughter-in-law.Perhaps out of this feeling, he showed a fatherly affection towards Uttarā.

On an auspicious day, Uttarā got married to Abhimanyu, in the city of Upaplavya.

The period of marital bliss for Uttarā and Abhimanyu lasted for six or seven months only. In the battle of Kurukṣetra, when Abhimanyu died, his pregnant wife Uttarā fainted, hearing that news. Hearing her pitiful lamentations, Srī Kṛṣṇa consoled her. In Strī parva of Mahābhārata, Uttarā is also found to be bitterly lamenting, over the dead body of Abhimanyu.

At the time of Yudhiṣṭhira’s Aśvamedha Yajña, once again the royal family of Hastināpura was under the sway of misery. Uttarā’s son was born as a dead child, struck by the Brahmāstra of Aśvatthāmā.

After the death of her husband, this child was the only support of Uttarā’s life. So she was utterly broken at this. Hearing her painful lamentations, Kṛṣṇa came and consoled her. Ultimately, by the grace of Kṛṣṇa, the declining Kuruvaṃśa was saved. Uttarā’s child was revived. He was named Parīkṣit.

When Dhṛtarāṣṭra, Gāndhārī and Kuntī left Hastināpura and resorted to Vānaprastha, some ladies of the royal family followed them. Uttarā was also among them.

After sometimes, when Dhṛtarāṣṭra and others resorted to Vānaprastha, the Pāṇḍava(s) went to visit them in the tapovana. Uttarā also went along with them. Vyāsadeva was present there, and using his ascetic powers, he arranged a meeting between the dead and surviving members of the Kuru family. The dead members of the Kuru family descended from heaven to earth. Son met the parents, wife met the husband. Then Vyāsadeva said, the widows who wished to attain the abode of their husbands, shoud immerse themselves in Gaṅgā. though there is not a clear mention, it is probable that Uttarā at this time immersed herself in water; after that we have no mention of her.