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SUMMARY: The aim was to evaluate the partial replacement of synthetic DL-Methionine (DL-Met) by Herbal Methionine (H-Met) compared to DL-Met and L-Methionine (L-Met), and the effects on growth performance, fat metabolism, and serum biochemistry in broilers. A total of 600 1-d-old male Cobb500™ chicks (Cobb x Cobb) were distributed in a completely randomized design, five dietary treatments, six replicates of 20 birds each. Liquid L-Met was provided through carboys connected to the water line. Two positive control (PC) treatments were used, either connected to the regular water line (PC1) or to carboys (PC2). The treatments were: Negative control (NC—no Met supplementation); PC1 and 2 (100% DL-Met); 60% DL-Met + 40% H-Met through feed (TH-Met); and 50% DL-Met + 50% L-Met through water (TL-Met). At 10, 22, and 42 d body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were determined. At day 21, serum and liver samples were used to evaluate serum biochemistry and the expression of genes related to fat metabolism, respectively. At 42 d, abdominal fat was weighed from 3 birds/replicate. In general, birds fed NC showed lower BWG, FI, higher FCR, and tended to have higher fat pad compared to the other treatments (P < 0.05). No differences were found for gene expression (P > 0.05). For serum biochemistry, Aspartate amino transferase (AST) level was higher in birds fed NC and TH-Met than in PC2 and TL-Met (P < 0.05). In conclusion, DL-Met can be partially replaced by H-Met without negatively affecting growth performance, fat metabolism, and serum biochemistry of broiler chickens.