LS4 will have a unique impact on multi-messenger astronomy (MMA) with its combination of wide-field, southern location and red sensitivity. Considering searches for gravitational wave and neutrino counterparts, LS4’s wide area will play a key role in mapping out the variable sky, and thus reject background variability for any searches for counterparts in southern MMA events. In addition, LS4’s wide area will be key in scanning poorly localized MMA events in regions with low galactic extinction, targeting fields of interest twice each night in g+i or i+z, allowing for >5000 sq. deg. to be scanned each night.