Some examples of large company websites that use WordPress are AAA, TheWaltDisneyCompany.com, RollingStones.com, BBCAmerica.com, and Bloomberg.com.
To view examples of smaller companies with professional WordPress websites, see this collection of websites by M5 Design Studio.
WordPress is the platform used by 35% of the web, so there are numerous examples of effective WordPress websites. To learn more, see our article “8 Big Brands that Use WordPress.”