Business environment regulations constituted critical determinants of enterprise competitiveness in industrial settings, particularly in emerging economies where regulatory frameworks were evolving. Mbarara Industrial Park, established in 2019 as part of Uganda's industrialization strategy, provided a unique context for examining how regulatory environments influenced competitive capabilities of enterprises. The park hosted 47 registered enterprises across manufacturing, agro-processing, and light industry sectors as of December 2023. This study investigated the effect of business environment regulations on enterprise competitiveness within Mbarara Industrial Park, conducted between October 2023 and March 2024. Regulatory frameworks examined included tax regulations, labor laws, environmental standards, licensing requirements, import-export procedures, and quality certification standards. Enterprise competitiveness was conceptualized as the ability to maintain and expand market share while achieving profitability and operational efficiency. The research employed a descriptive cross-sectional design utilizing mixed methods approaches. The entire population of 47 registered enterprises in Mbarara Industrial Park constituted the study's sampling frame, from which 42 enterprises participated, representing an 89.4% response rate. Purposive sampling selected key respondents including general managers, operations directors, and compliance officers from participating enterprises. Data collection instruments included structured questionnaires administered to 42 enterprise representatives and in-depth interviews with 8 regulatory officials from Uganda Revenue Authority, National Environment Management Authority, Uganda National Bureau of Standards, and Mbarara City Administration. Secondary data were obtained from enterprise performance reports and regulatory compliance records. The questionnaire demonstrated reliability with Cronbach's Alpha of 0.876. Data analysis employed SPSS version 28, utilizing descriptive statistics, Pearson correlation, multiple regression, and thematic analysis for qualitative data. Findings revealed that business environment regulations significantly affected enterprise competitiveness (r=0.694, p