We thus explored the detailed role of circ‐CSNK1G1 in thyroid cancer and found that circ‐CSNK1G1 downregulation suppressed the proliferation, survival, and invasion of cancer cells and tumor growth in vivo in thyroid cancer, which was consistent with the role of circ‐CSNK1G1 in other cancers. The gene discussed is CSNK1G1; the disease is cancer.