The jazz-tinted song will appear on Cabello's forthcoming sophomore album, "Romance."
"Liar" arrived alongside another single from the album, "Shameless," in a release dubbed by the vocalist as "Installment One."
In a recent Instagram livestream, Cabello shared details about the genesis of both songs, which were written the same day.
"We did the idea for 'Liar' and then I was like, I have like 30 minutes left and I really wanted to make another song, make another idea. I basically had the chorus melody for 'Shameless,'" she said.
The accompanying visual for "Liar" arrived on September 12, after Cabello teased it as "the most fun video [she's] ever made."
The humorous video, directed by Dave Meyers, sees Cabello being stuck in a "Groundhog Day" loop, while she tries to escape her conflicting feelings.
The clip opens on the "Havana" singer on a date with her rich fiancé who seems to bore her. She suddenly starts choking and is propelled into a series of nightmares, in which she is attacked by an elephant, cyclists and even drones.
"Oh no, there you go, making me a liar/Got me begging you for more/Oh no, there I go, startin' up a fire," she sings in the chorus over jazzy horns.
"Liar" offers a first glimpse of Cabello's new album, "Romance," which will arrive at a yet-unknown date.
The full-length will mark her sophomore studio effort, following her critically-acclaimed 2018 album "Camila."
Although details about the project are still scarce, Cabello revealed that "Romance" will chronicle "the stories [she's] accumulated" over the past couple of years.
"These songs are basically the story of my life the past couple years and the stories I've accumulated. I knew for a long time I wanted my album to be called ‘Romance' because these stories are about falling in love," she said in a statement.
Since the release of her debut LP, Cabello has collaborated with a wide array of artists, such as Mark Ronson for "Find U Again" and Shawn Mendes for the award-winning "Señorita."
Discover the music video for "Liar":