Color-transition features of polydiacetylene (PDA) have gained attention in recent years owing to its potential use in a wide range of sensors. This paper investigates electrospinning of PDA and polyvinylpyrolidone (PVP) to develop thermochromic nanofibrous composites. Polymer mixtures at different mass ratios and concentrations were electrospun and characterized afterwards. SEM results showed successful electrospinning of continuous and bead-free nanofibers with different diameters depending on the mass ratio of PVP to PDA. The obtained fibrous mats were then photo-polymerized under UV irradiation, which led to generation of a blue color showing the self-assembly of diacetylene monomers. The colorimetric transition of the fibers was also investigated and a color change from blue to red occurred by heating the fibers up to 80 C because of the conformational alterations in the PDA molecules. FTIR and DSC analysis validated these findings as well. As a result, the fabricated nanofibrous composites are potentially appropriate candidates for sensing applications.