Mellat Park (Persian: Pārk e Mellat – پارک ملت‎‎), literally the Nation Park, is an urban park in Tehran, Iran.

It is one of the largest recreation areas in Tehran, situated at the foot of the Alborz mountains adjacent to Valiasr Street in the east, and extends to the Chamran Expressway (Parkway) and Seoul Street to the west. It is watered by the winter-snow streams coming down from Mount Tochal close to 4,000 m high.

The park lies in the southern grounds of Tehran International Fair and Enghelab Club. It has pathways for walking and shade for picnics and relaxation, as well as facilities such as snack bars, coffee shops, and a small aviary. There is also a cineplex at the edge of the park.

Before the 1979 Revolution, it was known as Shahanshahi Park (پارک شاهنشاهی – Pārk e Šāhanšāhi; “Park of the King of Kings”). It is also the location of one of the steam-powered locomotives used on the first Iranian railway section, built during 1886–1888 . The No. 664 locomotive was built by the Belgian Ateliers de Tubize and commissioned on 1887.

Mellat Park is home to the first musical fountains in Tehran. Since July 2008, they attract and entertain many families at night