<p>With the growing interest in hydrogen-enriched natural gas transport, understanding the effects of hydrogen on pipeline materials has become essential. This work investigated the mechanical performance of GB20# pipeline steel in an actual hydrogen-enriched natural gas environment, assessing tensile properties, fatigue life, and fracture toughness across varying hydrogen partial pressures. It was found that, compared to pure natural gas, the plasticity and fatigue life of both the base and weld metals significantly deteriorated in hydrogen-enriched conditions, with degradation levels increasing with hydrogen partial pressure. Additionally, fracture toughness in both metals declined in hydrogen-enriched environments. The weld metal displayed slightly lower sensitivity to hydrogen embrittlement than the base metal, may be due to the finer grain structure. These findings contribute valuable insights into the behavior of natural gas pipeline steels under hydrogen exposure, essential for safe hydrogen-blended natural gas applications.</p>