Smarhon district or Smarhoń district (Belarusian: Смаргонскі раён; Russian: Сморгонский район) is a district (raion) of Grodno region in Belarus. The administrative center is Smarhon. As of 2024, it has a population of 48,464.

Historically the district's center Smarhon was part of the Vilnius Voivodeship within the Grand Duchy of Lithuania until 1795. Forty percent of the names of Smarhon district's settlements have remained of the Lithuanian origin, while residents of Smarhon once spoke in the Eastern Aukštaitian-Vilnian dialect of Lithuanian language.