Otto III (c. 1265 – 25 May 1310), a member of the House of Gorizia (Meinhardiner dynasty), was Duke of Carinthia and Count of Tyrol from 1295 until his death.

Otto was a son of Duke Meinhard of Carinthia[1] and his wife Elisabeth of Bavaria, widow of the Hohenstaufen king Conrad IV of Germany.

Otto's sister Elizabeth was married to Rudolf's son Albert of Habsburg and became German queen in 1298.

When Duke Meinhard died in 1295, his sons inherited a well-organized country, as their father had laid the foundation for an efficient administration by fostering ministeriales and creating the Tyrolean Raitbuch (internal record book).

Otto's brothers Albert (d. 1292), Louis and Henry VI were appointed Vogts of the Bishops of Trent.