Bieber teased fans on Instagram with a picture of a selection of guitars, accompanied by the caption, "Acoustic album?".
The 20-year-old also a shared a video of him playing a song, which he captioned, 'Dust in the wind'.
Last month, Cody Simpson revealed that he was working on a "real cool acoustic project" with Bieber.
He said that the pair had been working in the studio together and hinted towards the end result being "a little more than a song."
Bieber recently published song snippets online, teasing other potential music the singer has been working on.