Poly(vinyl alcohol) electrospun nanofibrous (PVANF) membranes that could sensitively detect and adsorb metal ions were modified with spirolactam–rhodamineine derivatives (PVANF–SRD) membranes and sulfo-spirolactam–rhodamine derivatives (PVANF–SSRD) membranes. Surface chemistry and morphology during functionalization of PVANF membranes were monitored using Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). These two membranes could display real-time sensing by the naked eye based on ring-opening reaction of spirolactam–rhodamine derivatives induced by corresponding metals. PVANF–SRD and PVANF–SSRD membranes exhibited high selectivity and sensitivity toward Fe³⁺/Cr³⁺ and Hg²⁺, respectively. In terms of PVANF–SSRD membranes, adsorption capacity for Hg²⁺ in contaminated water was studied. Freundlich isotherm could better describe the interactions than Langmuir: K_f = 7.0175 mg g⁻¹ (r² = 0.9996) for Hg²⁺. The regenerability of these two membranes was investigated via Na₄EDTA solution treatment, and results demonstrated good sustainability in detection and adsorption efficiency.