The Grammy winner, 47, posted a pair of photos of their pampering for her fans on Instagram, each attached with loving heart emojis.
Both were all smiles in one shot as they cuddled for the camera in coordinating pink pajamas, Monroe wearing a sheet mask and holding one of their family dogs in her arms.
Another photo hinted manicures and pedicures were part of the festivities, Monroe resting her feet in a soaking tub and holding out her hands wide as she puckered up for the snap.
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Monroe’s twin brother Moroccan Scott appears to have skipped out on the spa night.
But he was by his sister and mom’s side in January, when the family made a trip to a museum with dad Nick Cannon.
“Celebrating today in honor of the Reverend Dr. Martin Luther King Junior at the Kidspace Children’s Museum,” Carey captioned an Instagram post of the trip, adding the hashtags “#Dream” and “#ThankYouDrKing.”
Carey and Cannon, who broke up in 2014 after six years of marriage, remain focused on spending time together as a family and have frequently been spotted on outings together — from fun-filled days at Disneyland to celebrating the twins’ birthdays to coloring eggs for Easter.
“It’s funny when they say ‘co-parenting’ — that phrase is a little redundant,” Cannon told PEOPLE in January. “You can’t co-parent, you have to parent, and that’s what we do well because when it comes to our children, we’re selfless individuals — they’re first.”
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Cannon, 37, also said the pair are trying to set an example for their young children by showing them the love that still exists between the friendly exes.
“You’re reminded that it’s all about unconditional love and they’ve got to understand that to its core,” he explained to PEOPLE.
“Whenever we can show that — even if we’re not together, [that] we love each other unconditionally — and become that fine example to our children, they’ll grow up to be good human beings, hopefully.”