On Thursday afternoon, the A-list couple headed to San Diego to visit a few deserving patients at Rady Children's Hospital.
In several pictures posted on social media, The Voice coach and her fiancé posed for selfies and chatted with new friends during their surprise visit.
"Today we received a surprise special visit from a couple of people you might recognize!" the hospital shared on Facebook with a compilation of photos. "Thank you to Miley Cyrus, Liam Hemsworth and The Happy Hippie Foundation for bringing joy and laughter to our patients!"
During their visit, Liam opted for a flannel button-down and jeans. As for Miley, everything was coming up roses with her floral romper, yellow hair-bow, pink jacket and matching boots.
"Thank you for having us today! Beautiful children everywhere!" Miley shared after her visit. "@liamhemsworth is OFFICIALLY a #happyhippie !!!! @happyhippiefdn."
"Queen Warrior!!!! Yes you are!!!!!" she added in a separate post with one of the hospital's smiling patients.
Launched in 2015, the Happy Hippie Foundation was established to help rally young people to fight injustice. Its various programs also help today's youth achieve positive outcomes in life.
It's been nothing short of a joyful holiday season for Miley and Liam who have documented much of their winter celebrations online.
Whether posing for family photos in front of the Christmas tree or showing off their ugly holiday sweaters, the pair hasn't been shy about expressing their love for the season and each other.
"My parents always made Christmas about others and I hope you find it in your heart to do the same! @happyhippiefdn is what I am most thankful for this year because of the purpose it gives me," Miley recently shared. "Without it I would feel so lost and useless on this planet! Thank you to all those who support our mission and I hope EVERYONE has a magically Merry whatever you celebrate!!!!!! #celebrateloveveryday."