Reconfiguring the spectral output of nonlinear metasurfaces after fabrication remains challenging. We address this by exploiting the nonlinear Pancharatnam–Berry phase of C₃ᵥ-symmetric plasmonic metasurfaces. By integrating two metasurfaces inside a multipass cell, we experimentally demonstrate continuous spectral tuning of second-harmonic generation (SHG) phase-matching peaks across a 900–970 nm pump range by rotating one metasurface relative to the other. The extracted geometric phase follows the 3σθ dependence, and a full 2π tuning cycle is completed with 120^∘ of physical rotation. This establishes geometric-phase metasurfaces as a reconfigurable nonlinear platform, where mechanical rotation enables post-fabrication and broadband tuning of nonlinear optical responses.