Biosimilar drugs are highly similar to an originator (reference) biologic, with no clinically meaningful differences in terms of safety or efficacy. As biosimilars offer the potential for lower acquisition costs versus the originator biologic, evaluating the economic implications of the introduction of biosimilars is of interest. Budget impact analysis (BIA) is a commonly used methodology. This review of published BIAs of biosimilar fusion proteins and/or monoclonal antibodies identified 12 unique publications (three full papers and nine congress posters). When evaluated alongside professional guidance on conducting BIA, the majority of BIAs identified were generally in line with international recommendations. However, a lack of peer-reviewed journal articles and considerable shortcomings in the publications were identified. Deficiencies included a limited range of cost parameters, a reliance on assumptions for parameters such as uptake and drug pricing, a lack of expert validation, and a limited range of sensitivity analyses that were based on arbitrary ranges. The rationale for the methods employed, limitations of the BIA approach, and instructions for local adaptation often were inadequately discussed. To understand fully the potential economic impact and value of biosimilars, the impact of biosimilar supply, manufacturer-provided supporting services, and price competition should be included in BIAs. Alternative approaches, such as cost minimization, which requires evidence demonstrating similarity to the originator biologic, and those that integrate a range of economic assessment methods, are needed to assess the value of biosimilars.