The Sierra del Ajusco-Chichinauhtzin, (Ajusco-Chichinautzin Mountain Range) also known as Serranía del Ajusco or Sierra de Chichinauhtzin, is a Mexican mountain range located between Mexico City and the states of Morelos and Mexico.

[1] It makes up the southern part of the mountain necklace that surrounds Mexico City.

Its maximum height is at the Cruz del Marqués peak on the Ajusco volcano (3,937 metres (12,917 ft)).

Ajusco is part of the geological subprovince of the lakes and volcanoes of the Anahuac, located within the Trans-Mexican Volcanic Belt.

[7][8] The area has diverse habitats and species due to its unique geographic and climatic conditions.