The study, entitled Wave 6, is part of UM's ongoing social media research which has surveyed over 40,000 adult internet users in 62 countries so far. The latest figures show a consistent decline in brand website visits since 2008.
Just over seven in ten of today's consumers have visited one of these sites in the past six months, down from around 85% four years ago.
"Consumers are continuing to move away from increasingly siloed brand websites, viewing it as a one dimensional experience compared to that offered by social media," the report stated.
"This drop in visiting brand websites is not confined to any one group or demographic. We are seeing this happening equally amongst men and women and across the age ranges too."
Brand websites were found to be most commonly used for information, with 25% of respondents saying the sites were a good place to "learn something new" and 23% using them to "keep up to date". But social networks were more popular venues for both of these tasks, scoring 36% and 27% respectively.
Brand websites were also outstripped by social media on a host of other tasks, with users far more likely to agree the networks were good venues to "feel like I belong", "change opinions" and "express myself".
But UM also suggested that many brand owners' existing social media strategies were undifferentiated, and that social media measurement needs to evolve to track effectiveness properly.
"It is no good spending time and investment on a social experience that you don't know the value of or it doesn't meet your brand's challenges," the report added. "It's necessary to look at both the consumer's needs and your own objectives if you are to build something that not only connects to the consumer but also helps build value for your brand."
Data sourced from Brand Republic; additional content by Warc staff