The flocculation performance of polydiallydimethylammonium chloride (PolyDADMAC) and polyacrylamide (PAM) in treating pulp and paper mill wastewater was investigated. The experiments were conducted in jars with varying concentrations of PolyDADMAC (0.4-2.0 mg L−1) and PAM (0.4-8.0 mg L−1). Rapid mixing at 200 rpm for 2 min, followed by slow mixing at 30 rpm for 10 min, and a settling time of 5 min were used. Polyacrylamide was added to the wastewater samples 45 s after the addition of PolyDADMAC. Turbidity, chemical oxygen demand (COD), and total suspended solids (TSS) reduction efficiency were the main evaluation parameters. The results showed that the combination of PolyDADMAC and PAM was effective in treating pulp and paper mill wastewater. Increasing the dosage of PolyDADMAC increased particle instability and produced small flocs, while the addition and increase of PAM increased floc size for a better synergistic flocculation process.