'What You Want' will serve as the lead single from the band's self-titled third album, which will be released on October 11.
Lead singer Amy Lee told MTV News that the single grew out of a simple jamming session with her bandmates.
"[Bassist] Tim [McCord] and [guitarist] Terry [Balsamo] and I wrote that song at my house in New York," she explained. "We were just jamming, like, recording demos, and obviously the song has grown a lot since then, with everyone else.
"For me, it was - and I need to remember this, so I can apply it in the future - it wasn't trying so hard to be some epic, massive chorus. I was just doodling around on the piano and the guys were like, 'Do that. Whatever you just did, that's an awesome melody.' And I was like, 'Really?' Sometimes you just need your friends to be like, 'Do that!'"
Listen to a preview of Evanescence's 'What You Want' below:
Speaking about the song's meaning, she added: "It's about freedom - that's definitely a constant theme on the record - but, it's like Evanescence, and me, and my relationship with the music and the fans, and coming to that [realization] of 'This is what I'm supposed to do... I want to do this.'
"And when it says, 'Remember who you really are,' that's exactly everything you could assume it means."
Evanescence's record label Wind-Up Records also revealed that the track will get a full preview in August.
The singer added that she hopes the band will be able to bring more rock to the charts and radio playlists.
"I feel like, not that I'm trying to do what's important for the music industry, I'm doing what I want - we're doing what we love," she said. "But, at the same time, it's so refreshing for us to play music that we want to hear.
"It rocks, and not that there's nothing going on that does, but less and less; that's definitely not what's dominating the airwaves. And it would be so amazing and it's totally our dream to have that happen for us; not even just for us, but, like, we want to hear rock music again."
Lee had recently described their new album as "more fun". She will also appear on a Muppets tribute album, with a cover version of 'Halfway Down the Stairs'.
Listen to Evanescence's 'Bring Me to Life' below: