The wrist-worn device was described as a health and wellness product, according to internal documents that Bloomberg said it had reviewed.
The product is a collaboration between the Alexa software team and Lab126, a Sunnyvale, California-based research and development and computer hardware company owned by Amazon that came up the Fire phone and Echo smart speaker.
Bloomberg said that it wasn't clear what stage the development was at or if the device will ever be commercially released.
Amazon said in an email that "we do not comment on rumors or speculation." The company's shareholders rejected proposals to curb and audit its facial recognition service on Wednesday.
Shares of Amazon were down 2.6% to $1,810.