The former Malcolm In The Middle star, a pal of Branson's, plans to turn his brief space adventure into a new book.
Berfield's spokeswoman says, "Justin considers Branson a genius and is one of the few people that he would follow just about anywhere.
"He's a frequent guest at Branson's ultra luxury island home, Necker, in the British Virgin Islands, and now he's heading into space."
Branson's White Knight Two commercial spacecraft will take off for the first time in late 2009 or early 2010, full of celebrities and space-loving rich kids.
The two-and-a-half hour trip is expected to include about five minutes of weightlessness in space.
Berfield's aide adds, "Justin will be joined by other celebrities with confirmed boarding passes, such as Madonna + Tom Hanks."
Source: WENN