Identifying tumor characteristics that correlate with metastasis and survival in patients with conjunctival melanoma can potentially lead to better outcomes through a better selection of patients for adjuvant treatments including potentially life-saving new melanoma therapy. The objective of this study was to validate the conjunctival melanoma staging criteria in the American Joint Committee on Cancer (AJCC) Cancer Staging Manual (8th edition) and explore the prognostic importance of tumor thickness, histologic ulceration, and sentinel lymph node biopsy (SLNB) findings in patients with conjunctival melanoma. This is a case series of 88 consecutive patients with conjunctival melanoma. Clinicopathologic characteristics were analyzed. Associations between pathologic characteristics and outcomes were studied using Kaplan-Meier survival analysis. Local recurrence, lymph node metastasis, distant metastasis, and disease-specific survival (DSS) were the main outcome measures. The study included 56 women and 32 men; the median age was 62 years. At presentation, 41 patients had T1 disease, 23 had T2 disease, 23 had T3, and 1 had T4 disease. Sixty-six patients had invasive conjunctival melanoma (median thickness, 1.56 mm), 17 had conjunctival melanoma in situ, and in 5 patients, tumor thickness could not be determined. Overall, 22 patients had ulceration. In total, 31 patients underwent SLNB, and 4 had a positive sentinel lymph node (SLN). The median follow-up time was 46.6 months. Overall, 12 patients had nodal metastasis at presentation or during follow-up, 19 patients had distant metastasis at last follow-up, and 14 patients died of the disease. Tumor thickness and ulceration were associated with increased risks of nodal metastasis, distant metastasis, and death from the disease. Overall, greater clinical T category at presentation was associated with increased risks of distant metastasis and disease-related death; however, the risks of distant metastasis and disease-related death did not differ between T1 (bulbar) and T2 (nonbulbar) tumors or between T2c,d (caruncular) and T1-T2a,b (noncaruncular) tumors. In patients who underwent SLNB, a positive SLN was associated with worse distant metastasis free survival and DSS. Consideration should be given to adding ulceration and emphasizing tumor thickness as the main determinants of pathologic T category for conjunctival melanoma in future AJCC classifications. The significant association between a positive SLN and worse DSS highlights the importance of SLNB for prognosis in patients with conjunctival melanoma and selecting high-risk patients for adjuvant drug treatment.