Flynn, who lives in Chicago, grew up in Kansas City, Missouri. She graduated from the University of Kansas, and earned a Master's degree from Northwestern University.

The plot of Sharp Objects revolves around a serial killer in a Missouri town, and the reporter who has returned to her hometown from Chicago to cover the event. Themes include dysfunctional families, violence and self-harm. Dark Places is about an woman who investigates whether or not her incarcerated brother was truly responsible for the murder of their family in the 1980s, which happened when she was a child during the era of panic about Satanic ritual abuse.

Both of Flynn's novels have received wide praise, including from authors such as Stephen King. In 2007 Sharp Objects was shortlisted for the Mystery Writers of America Edgar for Best First Novel by an American Writer, Crime Writers' Association Duncan Lawrie, CWA New Blood and Ian Fleming Steel Daggers, winning in the last two categories.