The Belle and Belle II experiment at SuperKEKB $e^+e^-$ collider both provide a unique environment for searches in the dark sector (DS), thanks to the well know collision conditions, clean experimental environment and, for the Belle II dataset, dedicated trigger lines for low multiplicity events. We present recent results on: search for inelastic dark matter with a dark Higgs boson; search for Axion-like particles (ALPs) in B meson decays; and a search for feebly interacting particles (FIP) as missing energy in B decays.