The　on-demand　modulation　of　defects　in　materials　for　the　effective　modulation　of　optical　nonlinearity　is　desirable,　while　it　remains　a　great　challenge.　In　this　work,　we　demonstrate　that　electrochemical　activation　is　a　facile　and　convenient　approach　to　modulating　the　broadband　third-order　nonlinear　absorption　of　nanoporous　tungsten　oxide　(WO3-x)　thin　film.　The　film　does　not　exhibit　optical　nonlinearity　at　the　initial　state,　while　shows　a　distinct　saturable　absorption　under　an　applied　voltage　of　-2.5　V　with　the　excitation　of　515,　800,　and　1,030　nm　laser.　The　nonlinear　absorption　coefficient　(beta(eff))　is　-766.38　+/-　6.67　cm　center　dot　GW(-1)　for　1,030　nm　laser,　-624.24　+/-　17.15　cm　center　dot　GW(-1)　for　800　nm　laser,　and　-120.70　+/-　11.49　cm　center　dot　GW(-1)　for　515　nm　laser,　and　the　performance　is　competitive　among　inorganic　saturable　absorbers.　The　activation　is　accomplished　in　2　min.　The　performance　enhancement　is　ascribed　to　the　formation　of　abundant　in-gap　defect　states　because　of　the　reduction　of　the　tungsten　atoms,　and　a　Pauli-blocking　effect　occurs　during　the　excitation　of　in-gap　defect　states.　The　small　feature　size　of　WO3-x　(similar　to　12　nm)　enables　the　effective　and　fast　introduction　and　removal　of　the　defects　in　porous　film,　and　accordingly　the　fast　and　broadband　modulation　of　optical　nonlinearity.　Our　results　suggest　a　controllable,　effective,　and　convenient　approach　to　tuning　the　nonlinear　absorption　of　materials.