Ardern was born in Hamilton, New Zealand, and grew up as a Mormon. She was raised in Morrinsville and Murupara, where her father, Ross Ardern, worked as a police officer. Her mother, Laurell Ardern ( Bottomley), worked as a school catering assistant. She studied at Morrinsville College, where she was the student representative on the school's board. She later went to the University of Waikato, graduating in 2001 with a Bachelor of Communication Studies (BCS) in politics and public relations.