The study, 'Trends Reshaping the Future of HR', says workers will find it easier to create and share information and ideas, and will increasingly define their own learning, career paths and their own performance feedback, rather than have these dictated by management or a centralised department such as HR.
The management consultancy also highlights the "sea change" effect of a new generation entering the workforce with different values and behaviours from their elders.
LinkedIn HR director Connie Gibney agreed that social media has started to alter employees' behaviour and working cultures. She said HR will need to stay "in tune" with the way social media is "invading" the workplace.
"You only need to look at the amount of young people coming into the workplace who use LinkedIn. Last year, we registered 30 million students and recent graduates on the site - the fastest-growing demographic," Gibney said. "Young people entering the workforce expect companies to have a presence on social media, whether that's in the recruitment process, ways of delivering learning or internal messaging."
She warned that HR must "not get left behind" and must ensure it "plays its part" in the way social media is adopted.
HR should play a "vital role" in building effective organisational cultures and incentives, and processes related to knowledge sharing, innovation and engagement, the study suggested.
Gibney said: "It is important a company's HR department doesn't put barriers around social media use, as that will only [come across] as a negative feeling towards employees.
"It's a proven business tool and HR must seize this opportunity to take ownership of social media away from marketing and IT because, before too long, it will start to have an impact on businesses' bottom lines."