To overcome the limitations of microwave absorbers including lack of multifunctionality and limited dynamic tunability across varying application scenarios, a tunable and flexible metasurface absorber based on graphene and vanadium dioxide (VO?) is proposed in this paper. When VO? is in the insulating phase and the graphene sheet resistance (R?) is 120 Ω/sq, the absorber exhibits tri-band absorption characteristics. Its absorptivity (A(ω)) exceeds 90% in the frequency ranges of 5.87-7.56 GHz, 15.42-21.99 GHz and 32.24-36.80 GHz, corresponding to relative bandwidths (RB) of 25.17%, 35.12% and 13.21%, respectively. When VO? is in the metallic phase and Rs is set to 80 Ω/sq, the absorber operates in a single-band mode, covering 17.08–36.14 GHz (RB = 71.63%) with A(ω) > 90%. Both A(ω) and RB can be dynamically tuned by adjusting R?. Furthermore, the proposed absorber exhibits polarization insensitivity and angular stability, maintaining high performance for incident angles up to 40° and 60° for triple-band and single-band operation, respectively. The proposed design in this paper enables flexible switching between triple-band and single-band absorption, while also possessing advantages such as flexibility, thinness and light weight, showing potential application value in electromagnetic modulation and conformal stealth technology.