Snap Inc. lured the head of global advertising sales at Amazon.com Inc. to be its new business chief, filling a vacancy left by the departure of influential former strategy chief Imran Khan.

Jeremi Gorman, who spent more than six years in ad sales at Amazon, joins Snap as chief business officer at a time when the company is struggling to keep people using its product regularly. The Snapchat parent in August reported its first quarterly decline in daily users following a troubled redesign.