In the title compound, C(29)H(21)O(3)P, a coumarin-substitued ylid, the P atom is linked to three benzene rings and a planar coumarin moiety via a methyl-enecarbonyl group. The bond lengths in the P=C-C=O fragment clearly indicate a delocalized system involving the olefinic and carbonyl bonds. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O inter-action that results in an S7 graph-set ring motif. In the crystal, mol-ecules are linked into a three-dimensional framework by C-H⋯O hydrogen bonds.