The non-native name of Croatia (Croatian: Hrvatska) derives from Medieval Latin Croātia, itself a derivation of the native ethnonym of Croats, earlier *Xъrvate and modern-day Croatian: Hrvati. The earliest preserved mentions of the ethnonym in stone inscriptions and written documents in the territory of Croatia are dated to the 8th-9th century, but its existence is considered to be of an earlier date due to lack of preserved historical evidence as the arrival of the Croats is historically and archaeologically dated to the 6th-7th century. The names of the Croats, Croatia and Croatian language with many derivative toponyms, anthroponyms and synonyms became widespread all over Europe.

There exist many and various linguistical and historical theories on the origin of the ethnonym. It is usually considered not to be of Slavic but rather Iranian language origin. According to the most probable Iranian theory, the Proto-Slavic *Xъrvat- < *Xurwāt- derives from Proto-Ossetian / Alanian *xurvæt- or *xurvāt-, in the meaning of "one who guards" ("guardian, protector"), which was borrowed before the 7th century. The relation to the 3rd-century Scytho-Sarmatian form Khoroáthos (alternate forms comprise Khoróatos and Khoroúathos) attested in the Tanais Tablets, near the border of present-day Ukraine and European Russia, although possible remains uncertain.

In 2005, it was archaeologically confirmed that the ethnonym Croatorum (half-preserved) is mentioned for the first time in a church inscription found in Bijaći near Trogir dated to the end of the 8th or early 9th century.

The oldest known preserved stone inscription with full ethnonym "Cruatorum" is the 9th-century Branimir inscription found in Šopot near Benkovac, in reference to Duke Branimir, dated between 879 and 892, during his rule. The inscription mentions:

The Latin charter of Duke Trpimir, dated to 852, has been generally considered the first attestation of the ethnonym "Chroatorum". However, the original of this document has been lost, and copy has been preserved in a 1568 transcript. Lujo Margetić proposed in 2002 that the document is in fact of legislative character, dating to 840.

In the Trpimir charter, it is mentioned:

The monument with the earliest writing in Croatian containing the native ethnonym variation xъrvatъ ([xŭrvaːtŭ]) is the Baška tablet from 1100, which reads: zvъnъmirъ kralъ xrъvatъskъ ("Zvonimir, king of Croats").

The exact origin and meaning of the ethnonym Hr̀vāt (Proto-Slavic *Xъrvátъ, or *Xurwātu) is still subject to scientific disagreement. The first etymological thesis about the name of the Croats stems from Constantine Porphyrogennetos (tenth century), who connected the different names of the Croats, Βελοχρωβάτοι and Χρωβάτοι (Belokhrobatoi and Khrobatoi), with the Greek word χώρα (khṓra, "land"): "Croats in Slavic language means those who have many lands". In the 13th century, Thomas the Archdeacon considered that it was connected with the name of inhabitants of the Krk isle, which he gave as Curetes, Curibantes. In the 17th century, Juraj Ratkaj found a reflexion of the verb hrvati (se) "to wrestle" in the name. A more contemporary theory believes that it might not be of native Slavic lexical stock, but a borrowing from an Iranian language. Common theories from the 20th and 21st centuries derive it from an Iranian origin, the root word being a third-century Scytho-Sarmatian form attested in the Tanais Tablets as Χοροάθος (Khoroáthos, alternate forms comprise Khoróatos and Khoroúathos).