Mount Guiwan is a mountain in the Sierra Madre range in Alfonso Castañeda, Nueva Vizcaya, Philippines.

No scientific survey has yet been conducted in the area but recent expedition to the mountain by the Nueva Vizcaya Mountaineering Society, Inc. led by NVMSI Founder Gene Basilio Jr. and President Raymond Zamora in September 2012 proved that civets, monkeys, and other wildlife still thrive in the forests of Mount Guiwan.

A waterfalls estimated to be one km long from its first drop down to the bottom flows from near the summit of the mountain.

Underneath Mount Guiwan, a tunnel that diverts water from the Casecnan River in Brgy.

Pelaway to Pantabangan Dam in Nueva Ecija was constructed by the Casecnan Multi-Purpose Transbasin and Power project contracted by California Energy.