Previous studies have demonstrated that Helianthus tuberosus L. polysaccharide (HTLP) exhibits potent immunomodulating activity. The aim of this study was to investigate the molecular mechanisms underlying this activity and explore its potential applications in various anti-inflammatory models. We examined the anti-inflammatory potential of HTLP using in vitro and in vivo models. In vitro, we assessed the impact of HTLP on the expression of key inflammatory genes (TNFA, IL1B, IL6, IL12B, IL23, CD40, CD80, CD274, CSF1, and NAMPT) in lipopolysaccharide (LPS)-stimulated THP-1 cells. In vivo, we employed rat pocket granuloma and formalin- and carrageenan-induced oedema models. HTLP significantly reduced oedema volume in the in vivo models. In the carrageenan-induced oedema model, HTLP exhibited efficacy significantly higher than that of ibuprofen, reducing oedema by 76% at 8 h (p < 0.01). In the air pouch granuloma model, HTLP showed comparable anti-inflammatory activity to ibuprofen. In the formalin-induced oedema model, HTLP reduced oedema, demonstrating less efficacy than ibuprofen, with a reduction of 58% versus ibuprofen’s 65% (p < 0.001). The anti-inflammatory mechanism of HTLP involves not only the suppression of pro-inflammatory cytokine expression (TNFA, IL1B, IL6, IL12B, IL23, CD40, CD80, CD274, and CSF1) but also the activation of cell survival and cellular defence mechanisms (NAMPT) and the upregulation of the anti-inflammatory cytokine (IL10). The observed biological activity of HTLP suggests its potential as a valuable therapeutic agent for inflammatory conditions. The combination of functional and molecular evidence demonstrates HTLP’s potent anti-inflammatory properties across multiple models, with efficacy approaching or exceeding that of ibuprofen in certain models. However, further studies are necessary to fully elucidate its mechanism of action and to evaluate its long-term efficacy and safety. © 2025 Elsevier B.V., All rights reserved.