Born in the city of Enugu, she grew up the fifth of six children in an Igbo family in the university town of Nsukka in southeastern Nigeria, where the University of Nigeria is situated. While she was growing up, her father James Nwoye Adichie was a professor of statistics at the university, and her mother Grace Ifeoma was the university's first female registrar. Her family's ancestral village is in Abba in Anambra State.
Adichie studied medicine and pharmacy at the University of Nigeria for a year and a half. During this period, she edited The Compass, a magazine run by the university's Catholic medical students. At the age of 19, Adichie left Nigeria and moved to the United States for college. After studying communications and political science at Drexel University in Philadelphia, she transferred to Eastern Connecticut State University to live closer to her sister, who had a medical practice in Coventry. She received a bachelor's degree from Eastern, where she graduated Summa Cum Laude in 2001.
In 2003, she completed a master's degree in creative writing at Johns Hopkins University. In 2008, she received a Master of Arts in African studies from Yale University.
Adichie was a Hodder fellow at Princeton University during the 2005–2006 academic year. In 2008 she was awarded a MacArthur Fellowship. She has also been awarded a 2011–2012 fellowship by the Radcliffe Institute for Advanced Study, Harvard University.
Adichie, who is married, divides her time between Nigeria, where she teaches writing workshops, and the United States.