Waldo Mountain is a summit in Lane County, Oregon, in the United States. with an elevation of . It is in the Waldo Lake Wilderness and the Willamette National Forest.
The mountain and nearby Waldo Lake were named for John B. Waldo, an Oregon jurist. The Waldo Mountain Fire Lookout stands at the summit.
Along with Cupit Mary Mountain, Waldo Mountain is a forested, extinct shield volcano. It is part of the Diamond Peak (Oregon) chain.