The Wannachawee Recipe (WCR) is a traditional Thai herbal formulation with a clinical history of use in psoriasis. An observational study conducted at Prapokklao Hospital reported that 93% of psoriasis patients showed good clinical responses. However, the absence of standardized quality control parameters remains a critical barrier to its pharmaceutical reproducibility, safety, and integration into mainstream clinical practice. This study established robust quality specifications and a phytochemical profiling for WCR, in accordance with the Thai Herbal Pharmacopoeia (THP) guidelines, to support its development from traditional use to a standardized therapeutic agent. A multimodal analytical approach was employed, integrating microscopic characterization, physicochemical evaluation, and advanced instrumental techniques. Phytochemical characterization was conducted using High-Performance Liquid Chromatography (HPLC) fingerprinting and Compact Mass Spectrometry (CMS). A validated HPLC method was developed to quantify trans-p-coumaryl alcohol, a key bioactive marker. Anti-inflammatory activity was further assessed by measuring inhibition of nitric oxide production. Physicochemical analysis established rigorous benchmarks, including ethanol-soluble extractive (8.73 ± 0.15% w/w), water-soluble extractive (18.89 ± 0.09% w/w), and loss on drying (<10%), which ensure long-term stability and microbial safety. CMS analysis successfully identified key chemical constituents, including alpha-amyrin, stemone, protocatechuic acid, and trans-p-coumaryl alcohol. HPLC fingerprinting demonstrated high batch-to-batch consistency, while quantitative analysis determined a trans-p-coumaryl alcohol content of 8.77 mg/g extract. Critically, biological evaluation showed that WCR exhibited potent anti-inflammatory activity by inhibiting nitric oxide production, with a superior inhibitory effect compared with the reference drug indomethacin. This study provides a preliminary scientific framework for the standardization of WCR. It defines precise quality specifications and a potential bioactive marker, establishing the rigor needed for regulatory certification and industrial production. This work connects traditional Thai medicine with evidence-based pharmaceutics, positioning WCR as a promising therapy for psoriasis.