Advanced Gastric Signet Ring Cell Carcinoma (SRCC) is characterized by aggressive behavior, high metastatic potential, and extremely poor prognosis. There is an urgent need for effective imaging modalities to evaluate systemic metastatic lesions and to dynamically monitor disease progression during treatment. We report a rare case of a 26-year-old female with advanced SRCC presenting with extensive systemic metastases, clinically staged as IV (cT4N3M1). High-frequency and conventional ultrasound imaging revealed metastatic lesions involving the scalp soft tissues, cervical lymph nodes, intercostal soft tissues, pancreatic-splenic hilum region, pelvic cavity, peritoneum and omentum. The ultrasonographic findings were highly consistent with contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) results. The patient received seven cycles of a modified BEMA regimen (oxaliplatin, leucovorin and 5-fluorouracil) combined with nivolumab. Serial ultrasound monitoring indicated continuous disease progression. Due to poor therapeutic response, the patient succumbed to acute obstructive renal failure caused by tumor progression seven months after diagnosis. This report provided a comprehensive ultrasonographic assessment of widespread and rare metastatic sites in advanced SRCC, a scenario seldom documented. The combination of high-frequency ultrasound and Super Microvascular Imaging (SMI) offered precise, radiation-free, and repeatable evaluation of both superficial and deep lesions, proving particularly valuable for real-time monitoring of treatment response in critically ill patients. These findings underscore the unique role of systemic ultrasound in enhancing metastatic detection and therapeutic evaluation for advanced SRCC.