Rare decays, mediated by flavour-changing neutral currents (FCNCs), are highly suppressed in the standard model (SM) and are consequently sensitive probes of physics beyond the SM. The LHCb experiment has produced a broad range of rare decays measurements, setting important constraints on new physics (NP). These proceedings summarise three recent representative results: a comprehensive analysis of the decay $B^0 \to K^{*0}\mu^+\mu^-$ which reinforces existing tensions with SM predictions in both branching fractions and angular observables, a search for the lepton flavour violating (LFV) decay $B^0 \to K^{*0}\tau^{\pm} e^{\mp}$ setting the most stringent limits to date on $b \to s\tau e$ transitions, and a test of lepton flavour universality (LFU) using $B_s^0 \to \phi \ell^+\ell^-$ decays which is the first LFU test with rare $B_s^0$ decays and includes the first observation of $B_s^0 \to \phi e^+e^-$. These analyses demonstrate the precision and reach of the LHCb rare decays programme which is setting increasingly stringent limits on NP.