Blake Shelton was delighted when he saw Gwen Stefani's 9-year-old son Apollo's outfit at her Hollywood Walk of Fame ceremony last month.

The country singer sat down for an exclusive interview with Entertainment Tonight. Shelton, 47, admitted that he was touched when he saw his stepson donning a blue blazer with denim jeans and brown cowboy boots at the event. Apollo looked like a young version of the "God Gave Me You" singer.

"When he came down that morning, I was so happy and excited," Shelton told ET. "He wears, like, athletic sweatpants or shorts all the time, so when he puts on the jeans and boots, it's like, you know, it just warms my heart. I mean, it really does to see him have a little bit of country flair to what he wears." 

The former "The Voice" judge shared that Apollo owns a cowboy hat. They reportedly bought him one and got the young boy to wear it more.

Shelton also shared a family photo from the event on Instagram. "If you look up star in the dictionary, you'd see @gwenstefani's picture. Congratulations Gwen on receiving your very well-deserved @hwdwalkoffame star today. I'm so proud of you always," he wrote in the caption.

Several of his fans congratulated Stefani in the comments section. However, many also noticed how Apollo and Zuma looked like Shelton.

"Okay, but her youngest in cowboy boots," one wrote with a smiling face with heart-eyes emoji. Another wrote, "It's the best! I love how much her kids adore Blake."

"Wow, the middle boy looks some like Blake! I know, but he does!" a second user wrote, pointing out Zuma and Blake's resemblance. A fourth user agreed, commenting, "I know it's impossible, but my husband and I were just saying the same thing! The oldest like her ex, the middle like Blake, the youngest like her!! lol"

Shelton and Stefani spend most of their time with her three boys -- Kingston, 17, Zuma, 15, and Apollo -- at their Oklahoma compound. Just recently, Kingston made his live music debut at Sheltons' restaurant bar, Ole Red, in Tishomingo, Oklahoma. Music runs in the family since aside from Shelton and Stefani, Kingston's dad is rocker Gavin Rossdale. 

"This is what Ole Red is all about," Shelton said of Kingston's music debut. "To give these new, developing artists a chance to perform, and Kingston is a prime example of that." 

Shelton has been close to his three stepsons. In an interview with People, he shared that he decided to quit "The Voice" to spend more time with Stefani's three sons.

"They've taught me something about myself that I never knew: I'm more than just a country singer or a goofy guy. I'm someone they actually lean on, and that's not a responsibility that I ever had and not something that I ever considered even being into," he said. "It's a different kind of self-worth. Maybe it's the opposite of self-worth because you put yourself way down on the rung, and they move up ahead of you."

Tags: Blake Shelton Gwen Stefani Apollo