We performed matrix‐assisted laser desorption/ionization (MALDI)‐time of flight (TOF) mass spectrometry‐based total serum N‐glycomics of healthy controls versus recurrent thyroid cancer patients, characterized individual and global patterns of serum glycoprotein N‐glycosylation, and discovered an association between thyroid cancer recurrence and serum N‐glycosylation. The gene discussed is ART4; the disease is thyroid cancer.