The only source for the life of Aulus Gellius are the details recorded in his writings. He was of good family and connections, possibly of Africa origin, but he was probably born and certainly brought up at Rome. He travelled much, especially in Greece, and resided for a considerable period at Athens. He studied rhetoric under Titus Castricius and Sulpicius Apollinaris; philosophy under Calvisius Taurus and Peregrinus Proteus; and enjoyed also the friendship and instructions of Favorinus, Herodes Atticus, and Fronto.

He returned to Rome, where he held a judicial office. He was appointed by the praetor to act as an umpire in civil causes; and subsequently much of the time which he would gladly have devoted to literary pursuits was occupied by judicial duties of a similar description. The precise date of his birth, as of his death, is unknown; but from the names of his teachers and companions he must have lived under Hadrian, Antoninus Pius, and Marcus Aurelius.

His only known work, the Attic Nights (), takes its name from having been begun during the long nights of a winter which he spent in Attica. He afterwards continued it at Rome. It is compiled out of an Adversaria, or commonplace book, in which he had jotted down everything of unusual interest that he heard in conversation or read in books, and it comprises notes on grammar, geometry, philosophy, history and many other subjects. One story is Androcles, which is often compiled into collections of Aesop's fables (but is not found there).

The work, deliberately devoid of sequence or arrangement, is divided into twenty books. All these have come down to us except the eighth, of which nothing remains but the index. The Attic Nights are valuable for the insight they afford into the nature of the society and pursuits of those times, and for its many excerpts from works of lost ancient authors.