A photometric study of the short-period eclipsing binary 1SWASP J204932.94-654025.8, showing strong third light

•We presented and analyzed the three-color light curves of J2049 for the first time.•The photometric solutions reveal that J2049 is a short-period W-subtype shallow contact eclipsing binary with strong magnetic activity.•We discovered the presence of a strong third light, with an average luminosity contribution of 31.3% of the total light.