Flow lithography (FL) is a microfluidic technique distinguished for its ability to produce hydrogel microparticles of various geometrical and chemical designs. While FL is typically performed in room temperature, this paper reports a new technique called low temperature flow lithography that uses low synthesis temperature to increase the degree of polymerization of microparticles without compromising other aspects of flow lithography. We suggest that decreased oxygen diffusivity in low temperature is responsible for the increase in polymerization. Microparticles that exhibit a higher degree of polymerization display a more developed polymer network, ultimately resulting in a more defined morphology, higher incorporation of materials of interest, and improved functional performance. This work demonstrates the increase in the degree of polymerization by examining the temperature effect on both the physical and chemical structures of particles. We show applications of this technique in synthesizing thin microparticles and enhancing microparticle-based detection of microRNA. Low temperature FL offers a simple and easy method of improving the degree of polymerization, which can be implemented in a wide range of FL applications.