The radioactive decay probabilities of various proton halo (p-halo) nuclei from parent isotopes in the superheavy (SH) region, Z =115–120, were analysed by taking the Coulomb and proximity potential as the interacting barrier. The nuclear decay half-lives (t$_{1/2}$), barrier penetrability and various other attributes for the decay of p-halo nuclei such as $^8$B, $^9$C, $^{11,12}$N, $^{17}$F, $^{17,18}$Ne, $^{23}$Al and $^{26,27,28}$P from the isotopes $^{261–278}$115, $^{264–279}$116, $^{267–284}$117, $^{271–283}$118, $^{274–288}$119 and $^{277–285}$120 are determined. From the determined decay lifetime values, it is understood that most of the p-halo decays are probable. The error bars in the halo radius are incorporated for the nuclear decay half-life for these p-halo nuclei. Moreover, the effects of shell closure in the daughter and the parent nuclei are also clear from the plots of calculated decay half-lives vs. neutron number of the daughter nuclei. Peak and dip in the plots show the closed shell effects of the parent and daughter nuclei respectively. We found the closed shell effect of the parent at Np ∼ 152 and closed shell effect of the daughter nuclei at Nd ∼ 132, 142. Further, we have analysed the Geiger–Nuttall (GN) plots of logarithmic half-life time vs. Q$^{−1/2}$ and the universal curve of logarithmic half-life time against negative logarithm of the barrier penetrability for the chosen p-halo decay from the SH parents, Z = 115–120 and are found to be linear. Also, we can find that the addition of proximity potential does not make any notable variation in the behaviour of the Geiger–Nuttall plots. Hence GN law is also applicableto p-halo decay.