Search for dark sector and rare decays at BESIII

The BESIII experiment has collected a large data sample of charmonium, charm mesons, hyperons, and other light mesons. These data provide a unique opportunity to explore the dark sector and rare decays. We present recent dark sector results from the BESIII experiment, including searches for sub-GeV dark matter in $\eta \to {\pi }^0+\text{invisible}$ and $J\mathrm{/}\psi \to \phi +\text{invisible}$, searches for dark baryon particles in ${\mathrm{\Xi }}^{-}\to {\pi }^{-}+\mathrm{i}\mathrm{n}\mathrm{v}\mathrm{i}\mathrm{s}\mathrm{i}\mathrm{b}\mathrm{l}\mathrm{e}$, and searches for light vector bosons in ${\chi }_{cJ}\to J\mathrm{/}\psi X$, where $X\to e^{+}{e}^{-}$. In addition, we also present the recent rare decay searches, including a search for $\psi \to e\mu$, as well as searches for several baryon number and lepton number violation processes, and searches for various charmonium weak decays.