| En Name: | Gornomariysky District |
| Ru Name: | Горномарийский район |
| Loc Name1: | Курыкмарий кундем |
| Loc Lang1: | Meadow Mari |
| Loc Name2: | Кырык мары кымдем |
| Loc Lang2: | Hill Mari |
| Image View: | Paiskyryk.jpg |
| Coordinates: | 56.325°N 45.777°W |
| Image Coa: | Coat of arms of Gornomariysky Raion.png |
| Federal Subject: | Mari El Republic |
| Adm Data As Of: | October 2014 |
| Adm Ctr Type: | town |
| Adm Ctr Name: | Kozmodemyansk |
| Selsoviet Type1: | Rural okrugs |
| No Of Selsoviets Type1: | 10 |
| No Of Rural Localities: | 241 |
| Mun Data As Of: | August 2014 |
| Mun Formation1: | Gornomariysky Municipal District |
| Mun Formation1 No Of Urban Settlements: | 0 |
| Mun Formation1 No Of Rural Settlements: | 10 |
| Area Km2: | 1730 |
| Pop 2010Census: | 25869 |
| Urban Pop 2010Census: | 0% |
| Rural Pop 2010Census: | 100% |
| Website: | http://gornomari.ru |
| Date: | December 2009 |
| Population of Gornomariysky District | |
| Label1: | 2010 Census |
| Data1: | 25,869 |
| Label2: | 2002 Census |
| Data2: | 29,203 |
| Label3: | 1989 Census |
| Data3: | 32,949 |
| Label4: | 1979 Census |
| Data4: | 68,476 |
Gornomariysky District (Russian: Горномари́йский райо́н; Курыкмарий кундем, Kurykmarij kundem; Кырык мары кымдем, Kyryk mary kymdem) is an administrative[1] and municipal[2] district (raion), one of the fourteen in the Mari El Republic, Russia. It is located in the west of the republic and is the only district on the right bank of the Volga River. It borders with Yurinsky District in the north, Kilemarsky District and the Chuvash Republic in the south, and with Nizhny Novgorod Oblast in the west. The area of the district is 1730km2. Its administrative center is the town of Kozmodemyansk (which is not administratively a part of the district).[3] As of the 2010 Census, the total population of the district was 25,869.
Within the framework of administrative divisions, Gornomariysky District is one of the fourteen in the republic. It is divided into 10 rural okrugs, comprising 241 rural localities. The town of Kozmodemyansk serves as its administrative center, despite being incorporated separately as a town of republic significance—an administrative unit with the status equal to that of the districts.
As a municipal division, the district is incorporated as Gornomariysky Municipal District. Its ten rural okrugs are incorporated as ten rural settlements within the municipal district. The town of republic significance of Kozmodemyansk is incorporated separately from the district as Kozmodemyansk Urban Okrug, but serves as the administrative center of the municipal district as well.
The district is a home of Hill Mari people, and the Hill Mari language is spoken there.