The singers, both known for their acrobatic vocal abilities, don’t hold back on Fall In Line – the latest cut from Aguilera’s upcoming album Liberation.
Both stars had teased the empowerment anthem on social media over recent days, and it finally landed online at 1pm in the UK.
Lyrics include: “Little girls, listen closely, ‘cause no one told me, but you deserve to know.
“That in this world, you are not beholden, you do not owe them your body and your soul.”
Both Aguilera and Lovato started their careers as very young teenagers, and the lyrics of the song consistently allude to negative experiences within the industry.
It’s one of two songs featuring Lovato to be released this week: she’ll also feature on the new Clean Bandit single Solo, due Friday.
This is the latest taste of Aguilera’s comeback era: her new single Accelerate was released earlier this month and has so far peaked at No24 on the Billboard Bubbling Under chart – effectively an extension of the Hot 100.
Aguilera has also announced The Liberation Tour dates for the US, slated to run from September to November.
Speaking in a recent Billboard profile, Lovato said of her duet buddy: “I have always looked up to Christina.
“I remember being at her concert and singing facing the crowd instead of the stage, knowing that that was exactly what I wanted to do in life.”
She added: “She speaks up for what she believes in and sends a positive message, which are two things I find extremely important when given the platform we are lucky enough to have.”
Fall In Line is Aguilera’s first single with a female artist since 2001, when she topped charts on a cover of Lady Marmalade with Lil Kim, Mya and Pink.
But in recent years she’s had success with the likes of A Great Big World on Say Something and Maroon 5 on Moves Like Jagger.
Liberation by Christina Aguilera, the new album, is out on June 15.