The "Make Me Like You" singer took to Instagram to share photos of the festivities -- which included Stefani's family -- and write some sweet messages to her handsome beau.
"Celebrating the birth of my #bestie #favorite @blakeshelton," Stefani captioned a goofy, candid pic of the country crooner balancing a small birthday gift on his head.
She also posted a sweet, PDA-packed photo of her giving Shelton a celebratory smooch. Stefani wrote, "I get to kiss on the birthday boy @blakeshelton #happybirthdaycowboy."
The former No Doubt frontwoman even gave followers a look at her boyfriend's adorable armadillo b-day cake, complete with decorative gold scales.
Sunday was also Father's Day, so the 47-year-old songstress made sure to snap an adorable photo of her dad, Dennis, in the midst of receiving a big bear hug and a kiss on the cheek from the birthday boy.
Later in the day, Shelton took to Twitter to thank his fans for all the kind messages, writing, "Thanks for all the happy birthday wishes!!! 41.... S**t man I'm beating the odds."
Over the weekend, Shelton and Stefani spent some quality time together hanging out on a boat and enjoying the sunset. Check out the video below for a look at the romantic outing shared by the singer and her "summer love.