The Jiangmen Underground Neutrino Observatory (JUNO) will be a 20kton liquid scintillator detector, currently under construction in southern China. JUNO will be instrumented with close to 18,000 20-inch photomultiplier tubes (PMTs), possessing the highest photocathode coverage of any kiloton-scale liquid scintillator or Cherenkov detector to date. With its first-rate size, PMT coverage and low-background levels, JUNO will have highly competitive sensitivity to extra-terrestrial MeV-scale neutrinos. To maximise its astrophysical potential, a dedicated multi-messenger (MM) trigger has been developed. The new system will allow for an unprecedented minimum energy threshold of O(10keV), monitoring an extensive energy band of all-flavour neutrinos. The MM trigger will rapidly remove PMT dark noise, filter 14C background events and search in real-time for transient neutrino signals. Upon the detection of an astrophysical neutrino burst, JUNO can communicate with global multi-messenger facilities on a millisecond time scale, allowing for rapid follow-up measurement campaigns across the various detectors.