The two-piece is held together with decorative beads that change color depending on the intensity of UV radiation.
An accompanying tag shows a color-coded chart, explaining the various UV levels and their safety range, and also advising the wearer the numbered factor sun cream they should put on at different stages.
It works even on cloudy days when people may not be so aware of the sun's danger.
The beads on the string tie-ups on the new bikini stay white or light purple if the UV rays are at unharmful levels but become dark purple if they have reached cancer-causing levels.
UV levels 0-2 are rated low, 3-5 are moderate, 6-7 high, 8-10 very high and 11+ extreme.
The SmartSwim UV Intensity Bikini has been made by Canadian company Solestrom.
It is available in sizes from 0-18 and A-DD cups.
"We realised consumers were already becoming far more conscious of the harmful effects of spending too long in sunlight but the demand for this bikini has been even stronger than we expected," Telegraph quoted a Solestrom spokesman, as saying.