The band's Mike Mills told Spin that Smith and guitarist Lenny Kaye appear on one of the 12 tracks from the now-completed Collapse Into Now. Smith performed at an REM tribute concert at Carnegie Hall last year.
Vedder contributes vocals to another song, titled 'It Happened Today'. The album is due for release in early 2011.
Comparing the Jacknife Lee-produced record to their last from 2008, Mills said: "With Accelerate we were trying to make a point by making the songs as short and as fast as possible.
"So we wanted this new one to be more expansive. We wanted to put more variety into it and not limit ourselves to any one type of song.
"There are some really slow, beautiful songs, there are some nice, mid-tempo ones, and then there are three or four rockers."
He added: "[It's a] very personal, very human record. Not only to [singer] Michael [Stipe], but personal and human in the sense of the narrative of the songs, the protagonists of the songs."