Research by the job search website revealed that a further 12 percent said they were planning to start using social network sites to check out poetential employees.
Of those that do research candidates on the web, 43 percent said they relied on search engines, while 12 percent admitted to checking Facebook, and another 12 percent preferred LinkedIn.
CareerBuilder also said that two in five employers said they had found content on a social network that dissuaded them from hiring a candidate.
Over a third said a social networking profile proved they had lied about their qualifications on their CV, while 13 percent claimed a potential employee had made discriminatory comments on their Facebook page and nine percent said provocative or inappropriate photographs had been posted on the account.
"Social networking is a great way to make connections with potential job opportunities in 2010 and promote your personal brand across the internet," said Farhan Yasin, president of CareerBuilder.
"Make sure you are using this resource to your advantage by conveying a professional image and underscoring your qualifications."
However, CareerBuilder urged candidates to be careful once they had secured a position as 28 percent of employers admitted to firing someone for content found on their social networking profile.
Furthermore more than two in four employers said this was because the employee had written negative comments about the company or another employee on their social networking page.