Google Inc. plans to begin selling digital books in late June or July, a company official said Tuesday, throwing the search giant into a battle that already involves Amazon.com Inc., Apple Inc. and Barnes & Noble Inc.

Google has been discussing its vision for distributing books online for several years and for months has been evangelizing about its new service, called Google Editions. The company is hoping to distinguish Google Editions in the marketplace by allowing users to access books from a broad range of websites using...