Background/Objectives: Obesity is a multifactorial metabolic disorder characterized by excessive adipose accumulation and dysregulated lipid and glucose homeostasis. Marine brown algae contain diverse bioactive compounds with potential metabolic benefits; however, the in vivo anti-obesity effects of Padina minor remain insufficiently characterized. Methods: This study evaluated the effects of P. minor ethanolic extract on adipose metabolism and metabolic parameters in obese rats induced by a high-fat diet (HFD). Male Wistar rats (n = 36) were rendered obese via HFD and treated with P. minor extract (25, 50, or 100 mg/kg BW) for 4 weeks, with orlistat (30 mg/kg BW) serving as a reference control. Body weight, food intake, Lee index, visceral fat mass, serum lipid profile, and glucose levels were assessed, alongside protein expression of PPARγ, CNR1, and ESR1 (ELISA) and gene expression of Pparγ and Adipor1 (qPCR). Phytochemical constituents were analyzed using GC–MS and LC–MS/MS. Results: P. minor extract significantly attenuated body weight gain, adiposity indices, and visceral fat accumulation compared with HFD controls (p < 0.05), and improved metabolic profiles by reducing total cholesterol, triglycerides, and glucose levels while increasing HDL-cholesterol. At the molecular level, treatment was associated with decreased PPARγ and CNR1 expression and increased Adipor1 and ESR1 expression. The highest dose (100 mg/kg BW) produced effects comparable to orlistat. Phytochemical analysis identified flavonoids and phenolic acids, including quercetin, catechin, chlorogenic acid, and p-coumaric acid. Conclusions: Padina minor ethanolic extract improves metabolic parameters and adipose tissue characteristics in HFD-induced obese rats, potentially through modulation of pathways related to adipogenesis and lipid metabolism, supporting its potential as a marine-derived nutraceutical candidate for obesity management; however, further studies are required to confirm its mechanisms and clinical relevance. © 2026 by the authors.