The Theme of Seleucia (Greek: θέμα Σελευκείας, thema Seleukeias) was a Byzantine theme (a military-civilian province) in the southern coast of Asia Minor (modern Turkey), headquartered at Seleucia (modern Silifke).

[1] In the 8th century, it is attested as a subordinate command, first under a tourmarches and then under a droungarios, of the naval theme of the Cibyrrhaeots.

[1][2] In the early 9th century, however, it appears as a small kleisoura (a fortified frontier command) sandwiched between the larger Byzantine themes of the Cibyrrhaeots, the Anatolics, and Cappadocia and the sea, and bordering on the Abbasid Caliphate's domains in Cilicia along the river Lamos.

[3][4][5] According to the De Thematibus of Emperor Constantine VII (r. 913–959), the theme was divided in two commands, one for the hinterland and a coastal/maritime one.

At the time, the mountainous interior of the region was predominantly inhabited by Armenians who had settled there over the previous century.