The global food industry annually generates large amounts of by-products, many of which are underutilized or used only for animal feed. Recently, the circular economy approach has gained importance, focusing on transforming waste into value-added products by repurposing them as raw materials. Pumpkin seed flour (PSF) is obtained as a by-product from the milling of the press cake produced during industrial pumpkin seed oil extraction. PSF is notable for its high protein (41%) and lipid (35%) content and a moderate amount of dietary fiber (4.3%). The objective of this work was to characterize the techno-functional, physicochemical, nutritional, and microstructural properties of pumpkin seed flour. PSF showed low moisture content (5.1%) and water activity (aw = 0.523) and an intense green color with L*, a*, and b* values of 47.6, 1.1, and 21.6, respectively. Regarding the techno-functional properties, PSF presented good emulsion activity (55%), high thermal emulsion stability (51%) and good water and oil retention. On the other hand, ATR-FTIR spectra showed signals at 1744 cm^-1, 2923 cm^-1, and 2854 cm^-1 consistent with the presence of triglycerides and phospholipids. Moreover, chromatographic analysis revealed that around 82% of the fatty acids in PSF were unsaturated, despite this PSF showing high oxidative stability by rancimat. Finally, confocal scanning laser microscopy showed that the main components of PSF were highly interrelated and, as expected, no intact structures were observed. These results demonstrate the potential of pumpkin seed flour to be included as an ingredient in more complex matrices, which could improve its nutritional and technological properties. This, in turn, will contribute to the circular economy approach by valorizing this industrial by-product in the development of new food products.