The aim of this study was to synthesize different multifunctional materials containing 5-(4-carboxyphenyl)-5,10,15-tris(4-phenoxyphenyl)-porphyrin and iron oxide magnetic nanoparticles (MNPs). Besides, a new type of polymeric material comprising the same porphyrin and a polysaccharide, k-carrageenan, was also developed. All synthesized materials were characterized by FT-IR, TEM, XRD, ¹H NMR, HPLC, UV–vis and fluorescence spectroscopy and tested as catalysts for the Knoevenagel condensation of aldehydes at room temperature. The best performing porphyrin–based catalyst, which also contain MNPs and a silica linker, was additionally tested for its capacity to detect CO₂. All synthesized materials tested as catalysts for the above mentioned reaction proved comparable efficiency providing the desired adducts in short reaction times and with high yields. The novel designed catalytic systems met the sustainable chemistry requirements because they can be recovered and several times reused.