This chapter explores idioms as exceptionally rich sources of conceptual blends within the framework of Conceptual Blending Theory (CBT), originally developed by Fauconnier and Turner. Idioms, often non-compositional and culturally embedded, require the integration of multiple input mental spaces to generate emergent meaning in the blended space that cannot be directly retrieved from the literal inputs alone. Unlike straightforward metaphorical mappings in Conceptual Metaphor Theory, idioms frequently involve selective projection, composition, completion, and elaboration processes that produce novel inferences and creative conceptual structures. Drawing on examples primarily from Turkish and cross-linguistic data, the analysis demonstrates how idiomatic expressions construct dynamic networks of blended spaces, highlighting vital relations such as cause-effect, analogy, and disanalogy. The study argues that idioms serve as prime empirical evidence for the cognitive mechanisms of blending, revealing how language users routinely perform complex conceptual integrations to convey nuanced, context-dependent meanings beyond literal interpretation. This approach underscores the complementary nature of CBT and metaphor theory in explaining figurative language creativity