Lignin is the most abundant aromatic biopolymer functioning as an integral compound of woody materials. In its unmodified form it shows limited water solubility and is relatively unreactive. Thus, biotechnological lignin valorisation for high performance applications is highly underexploited. To expand its application, a new synthesis route towards novel concrete dispersing agents was developed. The route relies on a lignin functionalization by enzymatic transformation. Screening of lignin modifying systems resulted in functionalized lignin polymers with improved solubility in aqueous systems. Due to grafting of sulfanilic acid or p‐aminobenzoic acid by fungal laccases, lignin became soluble in water at pH≤4 or pH≤7, respectively. Products were analysed and evaluated in miniaturized application tests in cement paste and mortar. Their dispersing properties match performance criteria of commercially available lignosulfonates. The study exemplifies new perspectives for the use of lignin.