The paper presents the findings of an experimental study on the microwave synthesis (MW) of inulin acetate and its possible application as bio-additive in poly(vinyl chloride) (PVC). The obtained inulin acetate has been identified and characterized by spectroscopic methods. Advantages of the MW compared with the conventional synthesis were defined. In order to evaluate possible application of the product as bio-based additive for polymers, effect of the inulin ester on PVC behavior and characteristics has been investigated by differential scanning calorimetry (DSC) and deformation upon extension. Experimental results show that in concentration range up to 30.0 wt. % the inulin ester influences positively the properties of PVC causing effect similar to plasticizing one. At concentration over 30 wt.% the ester shows more specific behavior, which will be further investigated. Conclusions about potential application of MW synthesized inulin acetate as bio-based additive for PVC have been drawn.