The spectroscopy and photo-induced dissociation of flavin mononucleotide anions in vacuo are investigated over the 300-500 nm wavelength range. Comparison of the dependence of fragment ion yields as a function of deposited photon energy with calculated dissociation energies and collision-induced dissociation measurements performed under single-collision conditions suggests that a substantial fraction of photo-activated ions decompose through non-statistical fragmentation pathways. Among these pathways is the dominant photo-induced fragmentation channel, the loss of a fragment identified as formylmethylflavin. The fragment ion specific action spectra reveal electronic transition energies close to those for flavins in solution and previously published gas-phase measurements, although the photo-fragment yield upon excitation of the S-2 <- S-0 transition appears to be suppressed.