Background and Objectives: Relapsed or refractory (R/R) B-cell non-Hodgkin lymphomas (B-NHL) remain associated with poor outcomes despite advances in chemoimmunotherapy and chimeric antigen receptor (CAR) T-cell therapy. Many patients are ineligible for or relapse after cellular therapies, highlighting the need for effective off-the-shelf immunotherapeutic approaches. CD20 × CD3 bispecific antibodies (BsAbs) redirect endogenous T cells against malignant B cells and have emerged as a promising therapeutic class in B-NHL. To summarize current clinical evidence regarding mosunetuzumab, glofitamab, epcoritamab, and odronextamab in B-NHL, focusing on efficacy, safety, and emerging therapeutic applications. Materials and Methods: A structured review of published phase I–III clinical trials evaluating the four currently approved CD20 × CD3 BsAbs in B-NHL was conducted. Efficacy outcomes, durability of response, and safety data were assessed across indolent and aggressive lymphoma subtypes. Results: CD20 × CD3 BsAbs demonstrated substantial and durable clinical activity in heavily pretreated B-NHL, including patients with prior CAR T-cell exposure. Mosunetuzumab showed high response rates and durable remissions in follicular lymphoma (FL), while glofitamab demonstrated significant efficacy in aggressive lymphomas, particularly diffuse large B-cell lymphoma (DLBCL). Epcoritamab exhibited consistent activity across lymphoma subtypes with favorable tolerability supported by subcutaneous administration and step-up dosing. Odronextamab also demonstrated clinically meaningful responses in both FL and DLBCL, including high-risk populations. Across studies, cytokine release syndrome (CRS) was the most common adverse event, predominantly low grade and manageable with established mitigation strategies. Immune effector cell-associated neurotoxicity syndrome (ICANS) was uncommon. Infections and hematologic toxicities, particularly neutropenia, represented clinically relevant adverse events across all treatment programs, highlighting the need for special supportive care. Conclusions: CD20 × CD3 BsAbs represent a major therapeutic advancement in R/R B-NHL, combining high clinical activity, manageable toxicity, and off-the-shelf availability. Their expanding integration into earlier treatment settings and combination strategies is expected to further reshape the therapeutic landscape of B-NHL.