•Electrocoagulation (EC) and active chlorine-based photoelectro-Fenton-like (PEF-like).•Acid blue 29 (AB 29) dyestuff removal on iron flocs (76–58%) by EC.•Residual AB 29 after EC was mineralized (100%) by •OH generated in PEF-like.•AB 29 dyestuff solutions of 150–300 mg L−1 COD having 2000 mg L−1 chlorides. This paper deals with the development of an innovative process combining electrocoagulation (EC) and active chlorine-based photoelectro-Fenton-like (PEF-like) methods for eliminating the Acid Blue 29 (AB 29) dye from synthetic water (initially having 150–300 mg L−1 COD, in 2000 mg L−1 NaCl at pH 7.3). The EC process was performed in a continuous EC reactor equipped with 1018 steel plates as sacrificial electrodes. The PEF-like electrolysis was carried out in a filter-press electrochemical reactor equipped with Ti|Ir-Sn-Sb oxides and stainless-steel plates as the anode and cathode, respectively. The hydrodynamics influence in terms of the mean linear flow rate (0.69 ≤ u ≤ 3.47 cm s−1) and current density (12 ≤ j ≤ 36 mA cm−2) in the continuous EC reactor was systematically examined. The best EC trial was achieved at j = 36 mA cm−2 and u = 0.69 cm s−1 reaching 62 % bleaching and 84 % COD removal. Then, the remaining solution after EC passed through the PEF-like process (adjusting the pH = 3 and the catalyst at 0.4 mM Fe2+), reaching complete discoloration and COD removal at 15 mA cm−2, 24.2 cm s−1. Hydroxyl radicals were responsible for the mineralization of the AB 29 dye in the PEF-like process. The obtained flocs after EC were analyzed by XRD, XRF, and FTIR to elucidate the removal pathway of the AB 29 dye on flocs. Finally, the carboxylic and inorganic byproducts produced during the incineration of AB 29 dye by PEF-like were followed by HPLC techniques.