The thermal and photostability of novel anthrapyrimidine-containing colorants obtained by the condensation of various substituted aromatic amines with 6-bromo-7H-benzo[e]perimidin-7-one are described. The colorants were characterised by proton nuclear magnetic resonance, elemental analysis and mass spectra. Thermogravimetric analysis showed that these colorants are thermally stable up to 250°C. The UV-visible absorption spectra of the colorants were studied in solvents of differing polarity; the colorants exhibited slight positive solvatochromism. The photostability studies in dimethyl sulphoxide solvent were recorded by monitoring photodegradation of the colorants spectrophotometrically using a standard calibration curve. All the colorants exhibited excellent photostability. The light fastness study of two colorants in polypropylene showcases their ability as useful colorants for plastics.