Theodoros 10 was son of Bikarios 2 (or perhaps "the Vicarius") (Θεόδωρος δέ, ὁ υἱὸς τοῦ Βικαρίου); a native of Little Arabia (i.e. Moabitis, see below), he was appointed patriarch of Antioch after the death of Theophylaktos 5: Theoph. AM 6243 (τῆς μικρᾶς Ἀραβίας ὁρμώμενος ἐχειροτονήθη πατριάρχης Ἀντιοχείας). The date was c. 751. For the expression "Little Arabia", see also Theoph. AM 6240.

For the post of vicarius in this area (under Roman rule), see Theoph. AM 6123 (in Sept. 629) (PLRE III, Theodorus 162); perhaps the office and title were retained under Arab rule and Theodoros 10 was son of an eighth-century incumbent.

Theodoros 10 was patriarch of Antioch from c. 751 to c. 773. In 756 he was exiled by the Arabs (cf. Sulayman 3) on the grounds that he was constantly sending information to the emperor about Arab affairs; he was sent to his home district of Moabitis (εἰς τὴν Μωαβῖτιν χώραν πατρίδα τε αὐτοῦ): Theoph. AM 6248 (Θεόδωρος ὁ πατριάρχης Ἀντιοχείας).

In 763 he found bishop Kosmas 4 of Epiphaneia guilty of disrespect towards sacred things; when Kosmas 4 then became an open iconoclast, Theodoros 10, jointly with the patriarchs of Jerusalem and Alexandria, Theodoros 12 and Kosmas 3, and their bishops, anathematised him at Pentecost (22 May) 763: Theoph. AM 6255 (ὃν κοινῇ γνώμῃ Θεόδωρος, ὁ πατριάρχης Ἀντιοχείας, καὶ Θεόδωρος Ἱεροσολύμων, καὶ Κοσμᾶς Ἀλεξανδρείας σὺν τοῖς ὑπ' αὐτοὺς ἐπισκόποις τῇ ἡμέρᾳ τῆς ἁγίας πεντηκοστῆς μετὰ τὴν ἀνάγνωσιν τοῦ ἁγίου εὐαγγελίου ὁμοφρόνως ἀνεθεμάτισαν ἕκαστος κατὰ τὴν ἑαυτοῦ πόλιν).

Patriarch of Antioch; he was dead by 787; he, Kosmas 3 and Theodoros 12 all accepted one another's synodika: Mansi XII 1135 (Θεοδώρῳ τῷ Ἀντιοχείας Θεουπόλεως sc. πατριάρχῃ).

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