Semnani (Persian: سمنانی) may refer to:
- Semnani language, one of the local languages of the Semnan Province of Iran
- Semnani languages, a group of Northwestern Iranian languages, spoken in Semnan province of Iran
- Semnani people, an Iranian people who primarily live in northern Iran and speak the Semnani language
- Ashraf Jahangir Semnani (1287–1386), a Sufi saint
- In biology
- Elachista semnani, a moth in the family Elachistidae
- Scrobipalpa semnani, a moth in the family Gelechiidae