The multifunctional structures and functions of metal-organic frameworks with enzyme-like activity make them promising for various applications. This study has shown Fe/Co-doped porphyrin metal-organic framework (PCN-224-Fe/Co) (PCN-224 = porous coordination network-224) efficiently catalyzed the substrates hydrogen peroxide (H₂O₂) and 3,3′,5,5′-tetramylbenzidine (TMB) to generate oxidized-TMB (oxTMB). The results of the kinetic experiments showed that PCN-224-Fe/Co had a greater affinity for TMB compared to PCN-224-Fe or PCN-224-Co. A selective colorimetric method for determining ascorbic acid (AA) was also successfully developed due to the peroxidase-like activity of PCN-224-Fe/Co. The linear concentration-response range was found to be between 1 and 200 μM with a detection limit of 0.2 μM. This research will facilitate the creation of peroxidase mimics utilizing porphyrin metal-organic frameworks for use in detective applications.