The European Union’s Carbon Border Adjustment Mechanism (CBAM) poses an unprecedented institutional and economic challenge to carbon-intensive export industries in developing nations. While existing literature heavily relies on macroeconomic simulations to forecast trade impacts, there is a critical gap in comparative sectoral assessments derived from firm-level empirical data. This study employs an Objective Multi-Criteria Decision Analysis (MCDA) integrated with the Entropy Weight Method (EWM) to evaluate the compliance readiness of four key Factories in Northern Iran sectors: iron and steel, aluminum, cement, and fertilizers. Drawing on primary survey data from 134 export-oriented enterprises, the research assesses sectoral preparedness across four core dimensions: Measurement, Reporting, and Verification (MRV) Capacity, Green Innovation, Green Supply Chain Management (GSCM), and Perceived Compliance Cost. By substituting subjective expert judgments with data-driven weighting methods, the findings reveal significant structural heterogeneity. The aluminum and fertilizer sectors exhibit a proactive adaptation trajectory supported by robust MRV frameworks, whereas the iron & steel and cement sectors exhibit a more reactive compliance approach, primarily constrained by digital accounting deficits and high third-party verification costs. Furthermore, GSCM emerges as a systemic vulnerability across all sectors, highlighting that exporters are absorbing regulatory shocks in isolation without integrated upstream support. Ultimately, the study underscores that surviving cross-border environmental barriers requires targeted macroeconomic interventions, emphasizing the urgent need for a localized national emission factor database, specialized green credit funds, and ecosystem-wide supply chain incentives.