Summary: The effects of methylated CDs, α‐ and β‐DMCD and α‐ and β‐TMCD on the crystallization behavior of P(3HB) have been investigated by employing DSC and polarized optical microscopy (POM). The crystallization and nucleation of P(3HB) was improved by an addition of appropriate amount of each methylated CD, while negative effect of miscible blend was observed when the amount of addition exceeds the optimum value for the maximum nucleating effect. β‐TMCD was shown to be the most effective for the enhancement of the P(3HB) crystallization, thought to be due to the possibility of IC formation with P(3HB).Plots of log{−ln [1 − X(t)]} versus log (t) for mixtures of P(3HB) with different CDs or talc, respectively.imagePlots of log{−ln [1 − X(t)]} versus log (t) for mixtures of P(3HB) with different CDs or talc, respectively.