Cyclic and high-polymeric phosphazenes that bear 4-(1-oxo-1-phenyl-2-propen-3-yl)phenoxy (4-oxychalcone) side groups have been prepared to study their photochemical behavior. Small-molecule cyclic trimers of the general formula N3P3R5R’, where R = phenoxy, 2,2,2-trifluoroethoxy, chloro, and 4-oxychalcone and R’ = 4-oxychalcone, were synthesized to model the cross-linking reactions at the high-polymer level. Single-substituent and cosubstituent polymeric phosphazenes [NPRR’]n, where R = phenoxy, 2,2,2-trifluoroethoxy, or 4-oxychalcone and R’ = 4-oxychalcone were also prepared. Their photolytic cross-linking was monitored by ultraviolet spectroscopy. The high-polymeric system is of interest for uses in photolithography, photocurable coatings, and the stabilization of nonlinear optical properties.