| Ostrołęka County | |
| Native Name: | Powiat ostrołęcki |
| Settlement Type: | County |
| Total Type: | Total |
| Image Map1: | POL powiat ostrolecki map.svg |
| Map Caption1: | Division into gminas |
| Subdivision Type: | Country |
| Subdivision Type1: | Voivodeship |
| Subdivision Name1: | Masovian |
| Area Total Km2: | 2099.32 |
| Population Total: | 88717 |
| Population As Of: | 2019 |
| Population Density Km2: | auto |
| Population Urban: | 3408 |
| Population Blank1 Title: | Rural |
| Population Blank1: | 85309 |
| Coor Pinpoint: | Ostrołęka |
| Coordinates: | 53.0667°N 55°W |
| Seat: | Ostrołęka |
| Parts Type: | Gminas |
| Parts: | Total 11 |
| P1: | Gmina Baranowo |
| P2: | Gmina Czarnia |
| P3: | Gmina Czerwin |
| P4: | Gmina Goworowo |
| P5: | Gmina Kadzidło |
| P6: | Gmina Lelis |
| P7: | Gmina Łyse |
| P8: | Gmina Myszyniec |
| P9: | Gmina Olszewo-Borki |
| P10: | Gmina Rzekuń |
| P11: | Gmina Troszyn |
| Blank Name: | Car plates |
| Blank Info: | WOS |
| Website: | https://powiatostrolecki.pl/ |
Ostrołęka County (Polish: powiat ostrołęcki) is a unit of territorial administration and local government (powiat) in Masovian Voivodeship, east-central Poland. It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998. Its administrative seat is the city of Ostrołęka, although the city is not part of the county (it constitutes a separate city county). The only town in Ostrołęka County is Myszyniec, which lies 380NaN0 north of Ostrołęka.
The county covers an area of 2099.32km2. As of 2019 its total population is 88,717, out of which the population of Myszyniec is 3,408 and the rural population is 85,309.[1]
Apart from the city of Ostrołęka, Ostrołęka County is also bordered by Pisz County and Kolno County to the north, Łomża County to the east, Ostrów Mazowiecka County to the south-east, Wyszków County to the south, Maków County to the south-west, Przasnysz County to the west, and Szczytno County to the north-west.
The county is subdivided into 11 gminas (one urban-rural and 10 rural). These are listed in the following table, in descending order of population.
| Gmina | Type | Area (km²) | Population (2019) | Seat |
| Gmina Kadzidło | rural | 258.9 | 11,399 | Kadzidło |
| Gmina Olszewo-Borki | rural | 195.8 | 10,759 | Olszewo-Borki |
| Gmina Rzekuń | rural | 135.5 | 10,757 | Rzekuń |
| Gmina Myszyniec | urban-rural | 228.6 | 10,459 | Myszyniec |
| Gmina Lelis | rural | 197.0 | 9,696 | Lelis |
| Gmina Łyse | rural | 246.5 | 8,421 | Łyse |
| Gmina Goworowo | rural | 218.9 | 8,311 | Goworowo |
| Gmina Baranowo | rural | 198.2 | 6,489 | Baranowo |
| Gmina Czerwin | rural | 171.1 | 5,107 | Czerwin |
| Gmina Troszyn | rural | 156.3 | 4,765 | Troszyn |
| Gmina Czarnia | rural | 92.5 | 2,554 | Czarnia |