The 25-year-old model and actress was previously in a relationship with the musician - whose real name is Annie Clark - for 18 months before their split last summer, and although the pair have parted ways, it seems a piece of their relationship will live on in St Vincent's upcoming sixth studio venture.
During an interview with The New Yorker, the 34-year-old singer revealed Cara will provide vocals on a track entitled 'Pills', which details St Vincent's use of drugs as a ''coping mechanism''.
In the song, the 'Paper Towns' actress sings: ''Pills to grow, pills to shrink, pills, pills, pills and a good stiff drink / pills to f**k, pills to eat, pills, pills, pills down the kitchen sink.''
Speaking about the song, St Vincent said: ''I was trying to hold on. I didn't have coping mechanisms for tremendous anxiety and depression. I was trying to get through pharmaceutically.''
The news comes after the 'Digital Witness' singer recently admitted fans can expect her new album to include tracks about her relationship with Cara, as it was ''a big part'' of her life that she won't shy away from.
She said: ''I've always kept my writing close to the vest. And by that I mean I'm always gonna write about my life. Sometimes, in the past, I did that way more obliquely than now. But it's almost like an involuntary reflex. I can't help but be living and also taking notes on what's going on, always trying to figure out how to put that into a song.
''And that does not mean there's literal truth in every lyric on the way. Of course not. But I can only write about my life, and that - dating Cara - was a big part of my life. I wouldn't take it off-limits, just because my songs might get extra scrutiny.
''People would read into them what they would, and you know what? Whatever they thought they found there would be absolutely right. And at the same time it would be absolutely wrong.''