"Today … there are no more restrictions on what name you can use," the company said in a post on Google Plus late Tuesday afternoon.
The company also apologized for "some unnecessarily difficult experiences for some of our users" as a result of its names policy being unclear.
"We hope that today's change is a step toward making Google+ the welcoming and inclusive place that we want it to be," it added.
When Google Plus first launched in 2011, it had a strict policy requiring users to use their real names, and it deleted accounts with pseudonyms, prompting complaints and criticism from users.
Critics argued that using real names could endanger people who share things like their political views and sexual orientation within certain countries and communities.
Nevertheless, Google even tried to require real names on its YouTube service for a time.
The company wasn't alone. Facebook still requires users to use their real names, arguing that "this helps keep our community safe."
Google later loosened its policy by letting some users use pseudonyms and letting YouTube users bring their user names into Google Plus.
In a 2013 interview with Reuters, one of Google's senior executives, Vint Cerf, gave his opinion that users should not be forced to use their real names, and he acknowledged that the names policy had been hotly debated within the company.
In recent years, a number of social networking apps that allow users to be anonymous have sprung up to fill the niche left open by the real name policies of Facebook and Google.