Shares of the footwear retailer rose about 19% before the bell, as it also reported a smaller-than-expected drop in comparable sales for the second quarter and profit above estimates.
Johnson, who will be retiring, will continue as executive chairman of the board through Jan. 31.
During her eight-year stint as CEO of Ulta Beauty, Dillon put much of her focus on expanding the retailer's e-commerce business — a strategy Foot Locker has also been investing heavily in.
She has also served as global chief marketing officer of McDonald's from 2005 to 2010.
The management change comes at a time when Foot Locker is focused on growing sales of Adidas's sneakers and other items at its stores to counter the shrinking presence of its biggest supplier Nike at the retail chain.
Foot Locker said on Friday its board has decided to split the chair and CEO roles, and Dona Young, the company's lead independent director, will become non-executive chair, starting February.