Background: Despite multidisciplinary therapies, prognosis of pts with resectable esophageal squamous cell carcinoma (ESCC) remains poor. Combining PD-1 blockade to neoadjuvant chemotherapy might be a feasible and effective strategy. Camrelizumab (an anti-PD-1 antibody) was approved for advanced or metastatic ESCC in the second-line setting and showed improved anti-tumor activity and survival benefit when combined with chemotherapy in multiple advanced tumors. Methods: In this NIC-ESCC2019 phase 2 study, histologically or cytologically confirmed ESCC pts (stage II-IVA) were enrolled to receive two cycles of neoadjuvant chemoimmunotherapy (NIC) with camrelizumab (200 mg on day 1) plus nab-paclitaxel (260 mg/m² in total on day 1 and day 8) and cisplatin (75 mg/m² in total on days 1-3) of each 21-day cycle, followed by esophagectomy. The primary endpoint was complete pathologic response (CPR) rate in the primary tumor. Besides, we also explored the relationship between the tumor genomic profile or primary-tumor microenvironment and the pathological response. Results: Between Jan 17, 2020 and Dec 8, 2020, 56 pts were enrolled. 51 pts underwent surgical resection, and all had complete tumor resection. CPR was achieved in 18 (35.3%; 95% CI, 21.7%-48.9%) pts; 12 (23.5%) pts had major pathologic response (MPR), and 21 (41.2%) had incomplete pathological response (IPR). Of note, 16 (31.4%) pts achieved CPR in both primary tumor and lymph nodes. The objective response rate was 66.7% (95% CI, 40.0-70.4). No in-hospital mortality occurred. The most common treatment-related adverse events (TRAEs) were decreased WBC (20 [36%] of 56 pts), vomiting (19 [34%]), and alopecia (18 [32%]). Grade 3 TRAEs only occurred in 6 (11%) pts, and there were no grade 4 or 5 TRAEs. The most common immune-related AEs included grade 1-2 rash maculo-papular (7 [13%]) and reactive cutaneous capillary endothelial proliferation (5 [9%]). Presence of mutations in CREBBP and KMT2D at treatment-naïve time-point was correlated with non-response group (IPR and stable disease) (CREBBP, p = 0.046; KMT2D, p = 0.047). Among the immune populations, CD8+, CD8+PD-1+ and CD8+PD-L1+ T cells increased significantly after two doses of NIC, especially in the CPR+MPR group (CD8+, p = 0.013; CD8+PD-1+, p < 0.001; CD8+PD-L1+, p = 0.068). Conclusions: The addition of camrelizumab to neoadjuvant chemotherapy in ESCC demonstrated promising efficacy with acceptable toxicity, supporting the further investigation in a randomized phase 3 clinical trial. Clinical trial information: NCT04225364