LAGUNA BEACH, Calif.—The head of Alphabet Inc.’s Waymo unit said it plans to launch its first commercial self-driving car service in the next two months and expects businesses to be among its biggest customers.

Speaking at The Wall Street Journal’s WSJ Tech D.Live conference on Tuesday, Waymo’s John Krafcik said the new service will charge individual passengers for rides as well as businesses, such as Walmart Inc., who want to pay to shuttle their customers to stores. The service will initially be available to a small group...