The only contemporary source for Sappho's life is her own poetry, and scholars are skeptical of reading it biographically. Later biographical accounts are also unreliable.
Strabo indicates that Sappho was the contemporary of Alcaeus of Mytilene (born c. 620 BC) and Pittacus (c. 645–570 BC), and according to Athenaeus, she was the contemporary of Alyattes of Lydia (c. 610–560 BC). The Suda, a 10th-century Byzantine encyclopædia, dates her to the 42nd Olympiad (612/608 BC), meaning either that she was born then or that this was her floruit. The versions of Eusebius state that she was famous by the first or second year of the 45th or 46th Olympiad (between 600 and 594 BC). Taken together, these references make it likely that she was born c. 620 BC, or a little earlier.
Judging from the inscribed chronology on the Parian Marble, she was exiled from Lesbos to Sicily sometime between 604 and 594 BC. If Fragment 98 of her poetry is accepted as biographical evidence and as a reference to her daughter (see below), it may indicate that she had already had a daughter by the time she was exiled. If Fragment 58 is accepted as autobiographical, it indicates that she lived into old age. If her connection to Rhodopis is accepted as historical (see below), it indicates that she lived into the mid-6th century BC.
An Oxyrhynchus papyrus from around AD 200 and the Suda agree that Sappho had a mother called Cleïs and a daughter by the same name. The papyrus line reads "She [Sappho] had a daughter Cleïs named after her mother." (Duban 1983, 121) Two preserved fragments of Sappho's poetry refer to a Cleïs. In Fragment 98, Sappho addresses Cleïs, saying that she has no way of obtaining a decorated headband for her. Fragment 132 reads in full: "I have a beautiful child [pais] who looks like golden flowers, my darling Cleïs, for whom I would not (take) all Lydia or lovely..." These fragments have often been interpreted as referring to Sappho's daughter, or as confirming that Sappho had a daughter with this name. But even if a biographic reading of the verses is accepted, this is not certain. Cleïs is referred to in Fragment 132 with the Greek word pais, which can as easily indicate a slave or any young person as an offspring. It is possible that these verses or others like them were misunderstood by ancient writers, leading to the biographical tradition which has come down to us.
Fragment 102 has its speaker address a "sweet mother", sometimes taken as an indication that Sappho began to write poetry while her mother was still alive. The name of Sappho's father is widely given as Scamandronymus, but he is not referred to in any of the surviving fragments. In his Heroides, Ovid has Sappho lament that, "Six birthdays of mine had passed when the bones of my parent, gathered from the pyre, drank before their time my tears." Ovid may have based this on a poem by Sappho no longer extant.
Sappho was reported to have three brothers: Erigyius (or Eurygius), Larichus and Charaxus. The Oxyrhynchus papyrus indicates that Charaxus was the eldest, but that Sappho was more fond of the young Larichus. According to Athenaeus, Sappho often praised Larichus for pouring wine in the town hall of Mytilene, an office held by boys of the best families. This indication that Sappho was born into an aristocratic family is consistent with the sometimes rarefied environments that her verses record.
A story recorded by Herodotus, and later by Strabo, Athenaeus, Ovid and the Suda, tells of a relation between Charaxus and the Egyptian courtesan Rhodopis. Herodotus, the oldest source of the story, reports that Charaxus ransomed Rhodopis for a large sum and that after he returned to Mitylene, Sappho scolded him in verse. Strabo, writing some 400 years later, adds that Charaxus was trading with Lesbian wine and that Sappho called Rhodopis Doricha. Athenaeus, another 200 years later, calls the courtesan Doricha and maintains that Herodotus had her confused with Rhodopis, another woman altogether. He also cites an epigram by Posidippus (3rd century BC) that refers to Doricha and Sappho. Based on this story, scholars have speculated that references to a Doricha may have been found in Sappho's poems. None of the extant fragments have this name in full but Fragments 7 and 15 are often restored to include it. Joel Lidov has criticized this restoration, arguing that the Doricha story is not helpful in restoring any fragment by Sappho and that its origins lie in the work of Cratinus or another of Herodotus' comic contemporaries.
The Suda is alone in claiming that Sappho was married to a "very wealthy man called Cercylas, who traded from Andros" and that he was Cleïs' father. This tradition may have been invented by the comic poets as a witticism, as the name of the purported husband means "Penis, from Men's Island."
Sappho's lifetime witnessed a period of political turbulence on Lesbos and saw the rise of Pittacus. According to the Parian Marble, Sappho was exiled to Sicily sometime between 604 BC and 594 BC and Cicero records that a statue of her stood in the town hall of Syracuse. Unlike the works of her fellow poet, Alcaeus, Sappho's surviving poetry has very few allusions to political conditions. The principal exception is Fragment 98, which mentions exile and indicates that Sappho was lacking some of her customary luxuries. Her political sympathies may have lain with the party of Alcaeus. Though there is no explicit record of this, it is usually assumed that Sappho returned from exile at some point and that she spent most of her life in Lesbos.
A tradition going back at least to Menander (Fr. 258 K) suggested that Sappho killed herself by jumping off the Leucadian cliffs for love of Phaon, a ferryman. This is regarded as unhistorical by modern scholars, perhaps invented by the comic poets or originating from a misreading of a first-person reference in a non-biographical poem. The legend may have resulted in part from a desire to assert Sappho as heterosexual.