The Grammy-winning rock troupe directed fans to its website arcadefire.com on Thursday evening after a low-quality version of the album turned up on the internet. The album had been set for release on Tuesday.
On the band's site, Reflektor's 14 songs play as a backdrop to a Brazilian film titled Black Orpheus.
The leak appeared alongside social media claims that a few music stores began selling the album early, reportedly Rollercoaster Records in Kilkenny, Ireland, and a Czech Republic retailer.
The rock collective has engaged in a lengthy promotional campaign for the new album, including playing shows under fake names, hiring graffiti artists to blitz neighbourhoods with the album's logo (in chalk) and high-profile performances on Saturday Night Live and The Colbert Report.
On Monday evening, Arcade Fire will perform a special concert from Capitol Studios in Los Angeles.
CBC Music and NPR will livestream the hour-long performance of songs from Reflektor, beginning at 10 p.m. ET.