Alegre River may refer to:

Brazil Alegre River (Espírito Santo) Alegre River (Goiás) Alegre River (Guaporé) Alegre River (Maranhão) Alegre River (Mato Grosso) Alegre River (Paraná) Alegre River (Rio de Janeiro)

Mexico Alegre River (Mexico)

Venezuela Alegre River (Venezuela)