The country crooner celebrated Stefani's 50th birthday with an adorable tribute post on social media that made fans swoon.
"Happy Birthday @gwenstefani!!!! I love you so much it’s actually stupid… And possibly illegal in the state of California,” he tweeted on Thursday.
Shelton, 43, and his fellow "The Voice" judge are reaching another milestone in their relationship next month: four years of dating.
The couple first met on the set of "The Voice" in 2014 and sparks quickly flew.
“It’s actually shocking that it has already been that long,” Shelton admitted to People in June. “It’s kind of a blur. It still feels like it’s pretty new to me. I guess it is, relatively. Four years isn’t forever, but man, it seems like it just happened in no time.”
If Shelton does throw Stefani a birthday party, he'd have to outdo the amazing pizza party she held at her house for Shelton's birthday back in June. She also gifted him a huge custom-made sign for his Oklahoma ranch.
Shelton also received handmade birthday cards from Stefani's kids. Kingston, 13, Zuma, 10, and Apollo, 5 (whom Stefani shares with ex-husband Gavin Rossdale) all spent time constructing their designs.
“Christmas, birthdays, any kind of holiday — they always sit down and take time to write a message and draw pictures or something,” he said. “Those are the coolest, coolest things, you know? It’s something I never experienced in my life. When they take time and actually make something, it’s pretty cool.”
Stefani was married to Rossdale between 2002 and 2016 while Shelton was married to Kaynette Gern between 2003 and 2006 and Miranda Lambert between 2011 and 2015.