<p>A switchable multifunctional metasurface based on vanadium dioxide (VO₂) and photoconductive silicon (PSi) is proposed in the terahertz band, which possesses the functions of absorption (ABS), linear-to-linear (LTL) and linear-to-circular (LTC) polarization conversion by utilizing the phase change property of VO₂. The absorptivity, polarization conversion ratio (PCR) and ellipticity (<i>χ</i>) are dynamically tunable by varying the conductivity of PSi. When VO₂ and PSi are in the metallic phase, the metasurface is treated as a broadband absorber with more than 90% absorptivity in 1.53–3.25 THz. When VO₂ and PSi are in the insulating phase, the metasurface acts as a LTL and LTC polarization converter. The LTL polarization conversion is achieved in 0.86–2.51 THz (PCR &gt; 90%). The left-hand circular polarization and the right-hand circular polarization are obtained at 0.80 THz and in 2.58–3.22 THz, respectively. The influences of electromagnetic parameters, polarization mode and incident angle on the absorptivity, PCR and <i>χ</i> are investigated. Specially, the wideband and high-efficiency performance of these functionalities is maintained for a wide-angle incidence. The capability of multifunctional switch and integration with ABS, LTL and LTC polarization conversion into a single structure possessing high-efficiency and broadband characteristics has potential applications in communications, sensors and physical detection.</p>