A fiber optic displacement sensor (FODS) using a transmission technique was developed to determine the purity of honey using glucose adulterant. This was achieved by detecting the output signal of pure honey and adulterated honey with different addition percentage volume of glucose. The honey sample was adulterated with different percentage of glucose ranging from 0-10%. Prior that, the performances of sensor is first demonstrated by sensing output signal without any sample in a quartz cell. The linearity obtained is more than 99% in the range of 0 mm to 2.5 mm and the sensitivity is 32.65 mV/mm. The result from performance of sensor towards pure and adulterated honey showed that the highest sensitivity of all samples was achieved at 10% concentration of adulteration and the lowest sensitivity was obtained at 0% concentration (pure honey). Thus, FODS based on transmission technique has a potential to act as honey purity sensor by detecting the contamination of adulterant substances present in pure honey. The faster, simpler and cheaper devise is a promising technique to be employed in food industrial sector. Fiber optic displacement sensor in detecting honey purity for glucose adulteration.