The 47-year-old singer posted a photo Friday of Shelton playing with 3-year-old Apollo as they enjoyed a family vacation.
"#summer2017 love u guys gx," she captioned the picture for her 6.8 million Instagram followers.
Stefani shared a snapshot last week of herself lounging by the pool in an unknown tropical location. She shares Apollo, 8-year-old Zuma and 11-year-old Kingston with ex-husband Gavin Rossdale, from whom she split in August 2015.
"I was in a band and free my whole life, so I always thought I would be really free with [my kids] and do whatever I wanted, like, 'Oh, I'll take them out of school,'" Stefani told People last week. "But you learn that when they have boundaries is when they feel the safest."
"The hardest thing to do is having a discipline chart and follow up on all those things," she added. "It's work, you know? But that's where you get the results."
"I see a constant fear of 'How am I gonna make sure these kids are good people?'" the star confessed. "I love when they still play and you're like, 'Oh good. They're still doing that.'"
Stefani and Shelton confirmed their relationship in November 2015 following their respective splits from Rossdale and Miranda Lambert. Shelton couldn't help but gush about the singer during an appearance on Today in June.
"We're just content and happy, and it's just an incredible feeling," the 41-year-old country star said. "Our hobby is just hanging out together. We're best friends."