<p>Green catalysts derived from biowastes like agricultural waste or biomass offers a sustainable option compared to catalysts obtained from commercial sources. This study emphasizes the effective synthesis of biodiesel production and Knoevenagel condensation using a sustainable catalyst derived from pineapple peels. The catalyst underwent characterization through a variety of techniques including Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), and energy-dispersive X-ray (EDX) methods. The catalyst's active sites consist of alkali metal oxides, hydroxides, and carbonates, which are essential for the formation of the desired products. The biodiesel was formed with high percentage conversion rate of 97.5%; however, Knoevenagel products were synthesized with an extremely high percentage yield, i.e. up to 96%. In addition, the products underwent characterization using ¹H and ¹³C nuclear magnetic resonance spectra. The study delved into the reusability and stability of the catalyst, showing the recyclability of up to four cycles with 79% yield, revealing encouraging results for potential industrial applications.</p>