Tomarinsky District (Russian: Томари́нский райо́н) is an administrative district (raion) of Sakhalin Oblast, Russia; one of the seventeen in the oblast.

[1] Municipally, it is incorporated as Tomarinsky Urban Okrug.

[4] It is located in the southwest of the Island of Sakhalin.

The area of the district is 3,169.3 square kilometers (1,223.7 sq mi).

[2] Its administrative center is the town of Tomari.