Enterprise architecture principles are important tool to steer transformations in an enterprise. Mostly they are expressed as plain text which makes them unsuitable for interpretation by the machine. Additionally, natural language expressions are open to multiple interpretations and ambiguities. An ontology-based representation of enterprise architecture model enables reasoning on these models and knowledge inside the models can be queried to validate architecture principles. This paper applies the ontology-based modeling approach to build architecture descriptions for a real banking enterprise and validates three of the selected architecture principle from the enterprise’s architecture guidelines. The validation results for the architecture principles matched the expected outcome. The results were additionally verified with the representatives from the case organization who confirmed the correction of the results.