  We examine the effects of R-parity violating (RPV) supersymmetry on the
two-photon B decays B -> X_s gamma gamma and B_s -> gamma gamma. We find that,
although there are many one-loop RPV diagrams that can contribute to these
two-photon B decays, the RPV effect is dominated by a single diagram. This
diagram, named here lambda-irreducible, has a distinct topology which is
irrelevant for the b -> s gamma amplitude at one-loop and has thus a negligible
effect on the one-photon decay B -> X_s gamma. We show that the
lambda-irreducible RPV diagram can give BR(B_s -> gamma gamma) ~ 5*10^(-6) and
BR(B -> X_s gamma gamma) ~ 6*10^(-7), which is about 16 and 5 times larger than
the SM values, respectively. Although the enhancement to the decay width of B
-> X_s gamma gamma is not that dramatic, we find that the energy distribution
of the two photons is appreciably different from the SM, due to new threshold
effects caused by the distinct topology of the RPV lambda-irreducible diagram.
Moreover, this diagram significantly changes the forward-backward asymmetry
with respect to the softer photon in B -> X_s gamma gamma. Thus, the RPV effect
in B -> X_s gamma gamma can be discerned using these observables.
