Ulrich III (c. 1220 – 27 October 1269) was the Lord in the March of Carniola from c. 1249 and Duke of Carinthia from 1256 until his death, the last ruler from the House of Sponheim.

Ulrich III was the eldest son of Duke Bernhard of Carinthia and his wife Judith, a daughter of the Přemyslid king Ottokar I of Bohemia.

[1] Already his father had endeavoured to assume the rule over the Carniolan march, which Ulrich could secure for himself by marrying Agnes of Andechs, the widow of the last Babenberg duke Frederick II of Austria.

[1] He had differences of opinion about his father's inheritance with his younger brother Philip, who had to prepare for an ecclesiastical career and was elected Archbishop of Salzburg in 1247.

When Duke Ulrich III died in Cividale del Friuli on 27 October 1269, both Philip and Ottokar II claimed his inheritance.