A flexible display substrate, a method for manufacturing the same, and a flexible display device are provided. The flexible display substrate includes a display region, an electrode bonding region, and a bending region between the electrode bonding region and the display region. The method includes: forming an inorganic film layer on the flexible display substrate, forming a first via hole penetrating the inorganic film layer in the bending region by using a single patterning process, where a sidewall of the first via hole is step-shaped, the inorganic film layer includes at least one of the following film layers: a barrier layer, a buffer layer, a first gate insulation layer, a second gate insulation layer and an interlayer insulation layer.