This systematic review evaluates the efficacy and safety of biologicals for chronic rhinosinusitis with nasal polyps (CRSwNP) compared with the standard of care. PubMed, Embase, and Cochrane Library were searched for RCTs. Critical and important CRSwNP-related outcomes were considered. The risk of bias and the certainty of the evidence were assessed using GRADE. RCTs evaluated (dupilumab-2, omalizumab-4, mepolizumab-2, and reslizumab-1) included 1236 adults, with follow-up of 20–64 weeks. Dupilumab reduces the need for surgery (NFS) or oral corticosteroid (OCS) use (RR 0.28; 95% CI 0.20–0.39, moderate certainty) and improves with high certainty smell evaluated with UPSIT score (mean difference (MD) +10.54; 95% CI +9.24 to +11.84) and quality of life (QoL) evaluated with SNOT-22 (MD −19.14; 95% CI −22.80 to −15.47), with fewer treatment-related adverse events (TAEs) (RR 0.95; 95% CI 0.89–1.02, moderate certainty). Omalizumab reduces NFS (RR 0.85; 95% CI 0.78–0.92, high certainty), decreases OCS use (RR 0.38; 95% CI 0.10–1.38, moderate certainty), and improves high certainty smell (MD +3.84; 95% CI +3.64 to +4.04) and QoL (MD −15.65; 95% CI −16.16 to −15.13), with increased TAE (RR 1.73; 95% CI 0.60–5.03, moderate certainty). There is low certainty for mepolizumab reducing NFS (RR 0.78; 95% CI 0.64–0.94) and improving QoL (MD −13.3; 95% CI −23.93 to −2.67) and smell (MD +0.7; 95% CI −0.48 to +1.88), with increased TAEs (RR 1.64; 95% CI 0.41–6.50). The evidence for reslizumab is very uncertain.