'Radioactive' - released on October 3 - is a one-off single ahead of her second studio album, which is due out next year.
The track was produced by Norwegian duo Stargate, whose credits include Rihanna, Katy Perry, Alexis Jordan and Jennifer Lopez.
The single artwork appears below:
The singer - real name Marina Diamandis - wrote in a blog post: "I wrote 'Radioactive' in New York in the middle of a heat wave.
"Introduced to a glittering new nightlife, I fell in love with New York; it has this magic, fizzing white energy that no other city in the world has. I felt happy and was inspired to write a song that felt light and euphoric, a more streamlined, minimalistic style of songwriting."
She continued: "I have changed my approach to songwriting completely, and as a result, written songs I would never have written on my own.
"I've been working hard on my new album for a year and a half and hope 'Radioactive' can tide you over until it's ready."
Diamandis also teased further details about her next project, adding: "I'd love to introduce you all to something soon. An ancient Greek tragedy, old Hollywood fantasy... 'Electra Heart'."
Marina and the Diamonds' debut LP The Family Jewels peaked at number five on the UK album chart last year.
> Marina and the Diamonds explains Electra Heart: 'She's not an alter ego'
Watch Marina and the Diamonds' 'Radioactive' music video below: