With increasing global sulfur dioxide (SO₂) emissions, it is crucial to utilize emitted SO₂ in the manufacture of industrially valuable products, such as thermoplastic polyurethane (TPU) elastomers. Herein, we developed a novel TPU elastomer with a polysulfite oligomer, derived from the copolymerization of SO₂ and propylene oxide (PO) as the soft segments (SSs). When the SS molecular weight was kept constant, the increase in hard segment (HS) content enhanced tensile strength but reduced stretchability. Meanwhile, when HS content was constant, both the tensile strength and stretchability decreased with increasing SS molecular weight. Furthermore, distinct micro-phase separation, moderately intense hydrogen-bonding interactions, and better crystallinity enhanced the mechanical properties of the elastomers. Notably, SO₂-based TPU elastomers exhibited superior mechanical properties to those of poly(propylene oxide)-based TPU elastomers obtained via the same route. Therefore, the use of SO₂-based oligomer diols in TPU elastomer construction enhances mechanical properties and provides a method for SO₂ utilization.