The song will be released at midnight ET (0500 GMT) on Thursday, Swift told viewers on ABC's "Good Morning America."
"I'm so excited to share with you that tonight, at midnight, I'll be putting out my version of my song 'Love Story,' which was originally on my album 'Fearless,'" Swift said.
"I've now finished rerecording all of 'Fearless,' which will be coming out soon. My version of 'Fearless' will have 26 songs on it because I've decided to add songs from the vault, which are songs that almost made the original 'Fearless' album, but I've now gone back and recorded those so that everyone will be able to hear not only songs that made the album but the songs that almost made it. The full picture!"
The original "Fearless," released in 2008, was the second studio album by Swift, who has risen from a country music singer who often opened for others to a US pop star in her own right.
The Grammy Award-winning singer-songwriter, who in November was voted artist of the year for the sixth time at the American Music Awards, also told her millions of followers on Twitter and Instagram about the new album.
She included a peek at the cover, a sepia photograph of her upper body, eyes closed and quickly turning her head so that her blond hair streams out behind her.
"It has 26 songs, including 6 never before released from the vault. Love Story (Taylor's Version) will be out tonight," @taylorswift13 said on Twitter.