Osowiec may refer to:

• Osowiec, Łódź Voivodeship (central Poland)
• Osowiec, Lubusz Voivodeship (west Poland)
• Osowiec, Masovian Voivodeship (east-central Poland)
• Osowiec, Łomża County in Podlaskie Voivodeship (north-east Poland)
• Osowiec, Mońki County in Podlaskie Voivodeship (north-east Poland)
• Osowiec, Zambrów County in Podlaskie Voivodeship (north-east Poland)
• Osowiec, Pomeranian Voivodeship (north Poland)
• Osowiec, Warmian-Masurian Voivodeship (north Poland)
• Osowiec, Słupca County in Greater Poland Voivodeship (west-central Poland)
• Osowiec, Złotów County in Greater Poland Voivodeship (west-central Poland)
• Osówiec, Greater Poland Voivodeship, Greater Poland Voivodeship (west-central Poland)
• Osowiec Fortress, Russian fortress built in the 19th century in modern-day Osowiec-Twierdza, defended during World War I, today in Poland

• Asavyets (disambiguation)
• Osovets (disambiguation)
• Osowiec-Leśniczówka, a village in Łomża County, Podlaskie Voivodeship
• Osowiec-Twierdza, a village in Gmina Goniądz, Mońki County, Podlaskie Voivodeship