A persistent challenge in sustainability transitions is the uneven uptake of interventions such as renewable energy projects, conservation measures and rewilding initiatives. These often encounter resistance that cannot be explained by economics, technical feasibility or governance arrangements alone. Instead, they hinge on questions of legitimacy and cultural alignment. Existing frameworks, including socio-ecological systems (SES) and cultural ecosystem services (CES), recognise human dimensions yet miss the symbolic dynamics through which interventions are interpreted, accepted or contested. Symbolic codes are patterned systems of meaning expressed through aesthetics, aspirational values and common practices in a particular context, which influence whether interventions are embraced, negotiated or resisted. This paper advances the Symbolic Ecology Framework (SEF), a conceptual framework for integrating symbolic codes as cultural variables in socio-ecological analysis. This conceptual contribution: (1) establishes theoretical premises for treating symbolic codes as cultural variables in socio-ecological analysis; (2) specifies six attributes (salience, valence, resonance, legitimacy, diachronic status, place-binding) drawn from cultural analysis and environmental research for systematic code assessment; and (3) proposes their aggregation into a Symbolic Alignment Index (SAI) for legitimacy alignment diagnostic purposes. An illustrative case study application to renewable energy siting demonstrates the framework's analytical logic. Finally, the empirical research agenda required to operationalise SEF is outlined, including protocol standardisation, validation studies and cross-context calibration.