Bailup is a Western Australian locality and rural residential estate located 62 kilometres (39 mi) north-east of the state capital, Perth along Toodyay Road. The area is split between the Shire of Toodyay and Shire of Mundaring, the latter of which contains most of the land area.
Bailup was named after a nearby creek and a police station and inn established on Toodyay Road in the 1840s. The name is of Noongar origin but its meaning is unclear. The name was approved in early 1999 by the Department of Land Administration.
Most of the locality is covered in open Jarrah, marri and wandoo woodland, with some areas of dense understorey vegetation. Nearby Morangup Hill, the main feature of a reserve managed by the Department of Conservation and Land Management (CALM) on the edge of the Avon Valley National Park, is a granite peak providing extensive views over the surrounding area and is home to several species of birds including the Square-tailed Kite. The Red Swamp Brook, which runs through Bailup, feeds a significant wetland area.
Morangup Estate, the main residential area, is located just to the north of Toodyay Road on the east bank of the Red Swamp Brook, and contains about 200 residents and a small commercial centre. Some hobby farms have been established on nearby cleared land. Plans to build a new estate 2 km south within the Mundaring boundary were submitted in 2004, with Mundaring council approving the rezoning at its June meeting.