Immunotherapy is a new treatment option for patients with esophageal squamous cell carcinoma (ESCC). However, no study has investigated the efficacy and safety of sintilimab combined with nanoparticle albumin-bound paclitaxel (Nab-PTX) and platinum as first-line treatment for metastatic ESCC. In this retrospective study, eligible patients with metastatic ESCC were administered sintilimab plus Nab-PTX, cisplatin, or nedaplatin for up to 4 to 6 cycles. Subsequently, patients without progressive disease (PD) continued to receive sintilimab every 3 weeks as maintenance treatment until unacceptable toxicity, PD, withdrawal of consent, or for up to 2 years. The primary endpoint was the objective response rate (ORR) and the secondary endpoints were progression-free survival (PFS), overall survival (OS), disease control rate (DCR), and safety. A total of 22 patients diagnosed with metastatic ESCC were enrolled, 1 patient reached a complete response (CR), 15 patients achieved a partial response (PR), 4 patients had stable disease, and 2 had PD. The ORR was 72.7% (16/22) and the DCR was 90.9% (20/22). The time to response was 1.9 months (95% confidence interval [CI]:1.7-2.2 months). The median PFS was 8.9 months (95% CI, 7.1-10.7 months), and the median OS was 19.0 months. Exploratory biomarker analysis revealed that lactic dehydrogenase (LDH) was a potential marker for OS, and patients with high LDH levels had shorter mOS (13.0 months, 95% CI:7.5-18.5 months). Treatment-related adverse events (AEs) occurred in 21 patients (95.5%), most of which were grade 1 or 2. No treatment-related deaths occurred in this study. The results of this study suggested that sintilimab combined with Nab-PTX and platinum in patients with metastatic ESCC had a significantly high ORR and encouraging mPFS and mOS. LDH was a potential marker for OS, and the safety profile was manageable.