Mambai may refer to:
- Mambai people, a people group also known as Mambae, Manbae or Maubere from Timor-Leste
- Mambai language (Timor), the language spoken by Mambai people from Timor-Leste
- Mambai language (Cameroon), a language also known as Mangbai or Mamgbay language from northern Cameroon and southern Chad