Research Aim: This study analyzes the application of Smart Costing based on the Activity-Based Costing (ABC) framework to support cost structure analysis and managerial decision-making related to operational efficiency at Alawi Catering, a micro, small, and medium enterprise (MSME) in Nunukan. Approach: A case study approach was employed using primary data collected through direct observation, in-depth interviews with the owner and staff, and analysis of financial documents. The ABC method was applied to identify activity-based costs, while Smart Costing was used to interpret cost behavior and support adaptive managerial decisions. Research Finding: The findings show that Smart Costing based on ABC provides a more detailed representation of operational cost structures and identifies cost-intensive activities. This approach does not directly indicate immediate efficiency gains but supports strategic evaluation of pricing feasibility, production planning, and cost control by revealing mismatches between cost structures and operational practices. Theoretical Contribution/Originality: This study extends the cost management literature by positioning Smart Costing as a decision-support-oriented development of ABC, emphasizing the managerial interpretation of activity-based cost information in culinary MSMEs in border areas. Practitioner/Policy Implication: The results offer practical guidance for MSMEs in resource-limited regions to identify high-cost activities, evaluate pricing strategies, and improve operational decision-making under uncertain demand. Research Limitation: The study is limited to a single MSME and short-term data, restricting generalizability and long-term performance assessment.