<p>Flexible photodetectors with wavelength-selective response are essential for next-generation wearable and bio-integrated optoelectronics. However, conventional devices typically rely on external filters or complex structures, limiting the flexibility, integration, and broadband applications. Here, we present a gate-tunable flexible photodetector based on asymmetric van der Waals heterostructures composed of graphene, Molybdenum disulfide and single-walled carbon nanotubes. The asymmetric design induces a built-in electric field, effectively suppressing dark current and enabling dynamic modulation of spectral responsivity via gate voltage. As a result, the device achieves switchable photoresponse peaks at 450 nm and 635 nm, demonstrating a high responsivity of up to 40.3 A/W and a specific detectivity of 1.3 × 10¹¹ Jones. Furthermore, the device maintains robust performance under mechanical deformation and gate voltages. This work offers a scalable approach to realize intrinsically wavelength-selective, high-performance photodetectors on flexible substrates, providing new opportunities for integrated, broadband, and flexible optoelectronic applications.</p>