We propose a simple geometric, highly responsive and miniaturized surface plasmon polariton microbiosensor using a photonic quasicrystal fiber. Here, we consider gold as plasmonic material as the external coating for exciting the surface plasmon to detect the refractive index of the external analyte sensing to facilitate the practical realization. Further, we carry out detailed characteristics evaluations such as wavelength and amplitude sensitivities, resolution, full-width at half maximum, the figure of merit, signal to noise ratio and detection limit for both 6-fold and 8-fold plasmonic sensors. The proposed 6 and 8-fold sensors show a maximum sensitivity of 28,000 nm/RIU for an analyte range of 1.41–1.42 and 27,000 nm/RIU for an analyte range of 1.4–1.41, respectively. While the figure-of-merit of the 6-fold sensor is 491, for the 8-fold sensor, it is 231. Besides, the structural parameters and the arrangements of the air-holes in cladding region add to the sensing performance. The proposed sensing systems operate for a wide range of wavelengths from 600 to 1300 nm. Thus, the proposed sensors might turn out to be promising candidates for the refractive index-based biological and chemical detections. © 2019 The Authors