LOS ANGELES >> Last July, Luke Bryan and Carrie Underwood ran into each other backstage at Bridgestone Arena in Nashville, Tennessee — a familiar haunt for two veteran country stars with more than 50 No. 1 hits between them. The singers were there to take part in a concert tribute to the late Toby Keith, who died in February 2024. But between reminiscences, Bryan and Underwood shared a few hush-hush words about the future.

“Luke was like, ‘I hear you’re going to the circus,’” Underwood recalled recently with a laugh.

The circus was “American Idol,” the televised singing competition that launched Underwood’s career when she won in 2005 at 22. And indeed, news broke within a few days of the Keith tribute that she’d agreed to return to the show, this time as a celebrity judge alongside Bryan and Lionel Richie. Now, nearly 20 years after host Ryan Seacrest crowned a sobbing Underwood before a TV audience of about 30 million viewers, “Idol’s” 23rd season will premiere Sunday night on ABC.

“Carrie being here has felt so right,” said Bryan, who joined “Idol’s” judging panel in 2018 with Richie and Katy Perry. “It’s full-circle for her, and for us it’s been fun to hear her talk about —”

Underwood interrupted her cast mate in an exaggerated old-person voice: “Back when I was on the show…”

In many ways, “American Idol” — the No. 1 program on broadcast television for much of its first decade — hasn’t changed since it debuted in 2002 as a stateside extension of the U.K.’s “Pop Idol.” Amateur singers still reach for lung-busting high notes; judges still dispense advice drawn from their professional experience; Seacrest still emcees the proceedings with a knowing amusement.

Yet the world around “Idol” has transformed dramatically. For one thing, the show has acquired more competition in the form of “The Voice” and “America’s Got Talent” even as the rise of streaming has cut into the audience for broadcast TV. (Last year’s finale drew only around 5 million viewers.) The music industry is different too — controlled far less from the top down than it was a decade or two ago thanks to social media, which nowadays is where stars are born and hit records are made. (“Inside Your Heaven,” Underwood’s debut single after winning “Idol,” sailed to No. 1 on Billboard’s Hot 100, whereas Abi Carter, Season 22’s victor, has yet to crack the chart.)

The team behind “American Idol” frames the show’s steadfastness as a selling point in an era of digital overload and cultural upheaval. “It’s a safe place to go where you know what to expect,” said Seacrest, who likened the show to the venerable “Wheel of Fortune,” which has seen a ratings bump since he took over last fall as host from Pat Sajak. And with Underwood replacing Perry, who left after Season 22, “Idol” seems eager to evoke memories of the glory days.

“I was just watching a tape of Carrie this morning at the Orpheum Theatre, when she was flown on a plane for the first time to come out to Hollywood Week” as a contestant during Season 4, Seacrest said. “I asked her if she’d seen any stars since she got here, and she looked up at the sky and said, ‘No, it’s been pretty cloudy.’”

Underwood, now 41, was back at the Orpheum on a Monday morning in January for this year’s Hollywood Week, when hopefuls who earned a golden ticket during the show’s lengthy auditions vie for the chance to perform live for “Idol’s” voting audience. As young singers could be heard warming their voices upstairs, Underwood sat on a sofa in a basement lounge chatting with Bryan, 48, and Richie, 75, about what they did over the weekend — Bryan played golf at the Bel-Air Country Club — and about the previous evening’s AFC Championship football game. An assistant came by and offered to fetch different bottles of water than the ones sitting in front of the judges.

“Don’t go writing that she’s persnickety about her water,” Underwood joked.

To hear the country star tell it, deciding to do “Idol” again — to “join this crazy bunch,” as she put it — didn’t require loads of deliberation. “I feel like I’m at a point in my career where I just want to do things I want to do — things that sound like fun, sound like a challenge,” said Underwood, whose popular residency at Las Vegas’ Resorts World casino is set to conclude next month after more than three years. “This felt exciting to me.”

“Idol” showrunner Megan Michaels Wolflick noted that the show has never had a former competitor return as a judge, though well-known “Idol” alums like Kelly Clarkson and Jennifer Hudson have put in time assessing singers on “The Voice.” (Among the stars who’ve served as judges on “Idol” are Jennifer Lopez, Mariah Carey, Steven Tyler and Nicki Minaj.) “And Carrie’s our queen as far as being the biggest-selling ‘Idol’ winner in history,” Wolflick added. “So it made so much sense for her to come on.”

Finding the right tone behind the judges’ table — firm yet supportive, kind yet realistic — has been a process for this denizen of nice-and-smiley Nashville. “I’m from the generation of brutal honesty: ‘You suck,’” Richie said. Underwood, on the other hand, “never wants to send anybody home,” according to Bryan. “She wants 150 winners of ‘American Idol.’”

“I just don’t want to do the wrong thing,” Underwood said. “Twenty years ago, the judges were having all these back-room conversations about me, looking at my little photo, thinking of which board to put me on. Luke and Lionel are like, ‘Just go with your gut,’ and I’m like, ‘Wait, let me check my notes!’”

Underwood is accustomed to being talked about: She angered some in January when she accepted an invitation to sing “America the Beautiful” at President Donald Trump’s second inauguration — a decision she made, she said at the time, in “the spirit of unity.” At the Orpheum a couple of weeks later, Underwood shrugged off the criticism. “No matter what you do, everybody’s gonna have some good stuff to say and some not-so-good stuff to say,” she said. “It’s just the world we live in, so you get used to it.”

Both Seacrest and Wolflick describe “Idol” as an intentionally apolitical enterprise. “It’s absolutely a strategy of the show to not be political ever,” Seacrest said, drawing a contrast between “Idol” and the network late-night shows. “They pick a side, right? That’s their target, and they decide to go one direction or the other to keep loyal fans. We want everybody.”

Did Underwood’s appearance with a polarizing president run counter to that position? “That was her decision to make in her career,” Wolflick said. “It wasn’t necessarily about us.”

Then again, it’s not at all clear that Underwood’s presence at the inauguration did anything to harm “Idol,” which boasts a strong following in red-state America. “There are a lot of small towns and medium-sized cities between New York and Los Angeles where this show is still something that people have an appointment to watch,” Seacrest said.