The aminolysis of five-membered cyclic carbonates which results in polyhydroxyurethanes (PHUs) is one of the most promising synthetic pathway to achieve isocyanate-free polyurethanes (NIPUs), one of the main industrial challenges over the coming years. This study highlighted the higher reactivity of β-hydroxyamines toward cyclic carbonate in comparison to classical alkylamines through the determination of their reaction rate constants. The key role of the β-OH substituent in the aminolysis was enlighten by a DFT investigation. Polyfunctional alkylamine and β-hydroxyamine were then used for the synthesis of fully biobased PHU thermosets. The higher reactivity of β-hydroxyamines was confirmed by the gelation time gap between the two formulations studied. After curing, the thermal and thermo-mechanical properties of the thermosets were compared.