Adult-onset Still’s disease (AOSD) is an uncommon inflammatory condition presenting with high grade fever, arthralgia, skin rash, and leukocytosis. Autoimmune thyroid disease (AITD) is commonly seen in females in their third to fifth decade and usually missed to screen in other autoimmune diseases. In this study, the case of a 17-year-old female patient from Pune is reported who presented to Bharati hospital in November 2020, with a six-month history of high-grade fever, arthritis, and elevated acute phase reactants along with hypothyroidism. She was diagnosed with AOSD (based on Yamaguchi criteria) and AITD with positive anti-thyroid peroxidase (anti-TPO) antibodies. She responded well to oral steroids and thyroid supplements. This case draws attention to the rare association between AOSD and AITD.