At some point, Kelly Clarkson decided to just be Kelly Clarkson.

If she wanted to go onstage barefoot, fine. If she wanted to buzz cut one side of her head and grow her hair out on the other, why not? If she wanted to strip down her big ballads and sing them with only piano accompaniment so the words would have maximum impact, so be it.

After years of trying to live up to someone else’s expectations (not just Clive Davis’) for America’s first “American Idol,” Clarkson chose to listen to her own voice. And it was pretty clear on Tuesday night at Xcel Energy Center in St. Paul that she knows who she is — or at least wants to be.

She may not be the best judge of material, and she has shown a tendency to chase trendiness (by collaborating with the likes of Dr. Luke, Max Martin and even Katy Perry and Sia). But she never looked more comfortable and confident onstage in the Twin Cities than she did on Tuesday.

To be fair, she hasn’t performed here all that often. Since she canceled a Minnesota State Fair performance on two hours notice in 2007, Clarkson shared a tour with Reba McEntire here in 2008 and headlined KDWB’s Jingle Ball in 2011. That’s not much in a 12-year, six-album career.

She made up for it Tuesday by being herself, filling the less than full arena with her personality and voice. She chatted with fans, answering questions about her height and telling the stories behind her songs. It wasn’t the kind of canned patter you hear at most concerts.

For a change of pace, Clarkson invited a fan onstage to sing, and Jeff Johnson killed it with Josh Groban’s “Remember When It Rained” — and Clarkson acknowledged both the song and his sparkly shoes.

Then Clarkson showed why she skyrocketed to fame on the first season of “American Idol.” It was time to interpret someone else’s hit, not just any hit but one with local ties. She turned Prince’s “Purple Rain” into some kind of soul opera and later mashed up the current Mark Ronson/Bruno Mars smash “Uptown Funk” with her own “Walk Away” into a let-your-hair-down-and-strut-barefoot-down-the-runway funk.

Those covers underscored why America fell in love with Clarkson on “Idol” and have continued to worship her. She has a glorious voice and a natural sense of emotionalism. Throughout her 90-minute set, she demonstrated the power, richness, soulfulness, control and range of her voice. She can wail and she can whisper with equal effect.

While her songs may recall those of Pink and Katy Perry, Clarkson’s voice and singing style evoke Ann Wilson of Heart. That was especially evident on guitar-driven tunes like “Nostalgia” but also on her anthem “Stronger,” which could well be her theme song.

Several times during the concert, Clarkson talked about the challenges in her life, including growing up with a bad dad and dating men who treated her as badly as her father had. But even though she said too many of her songs are depressing (they’re her therapy), her resilience in song (especially “Piece by Piece,” done with just piano and voice) and spirit (she talked about being a happy mom of a 1-year-old girl) clearly prevailed.

While Clarkson, at 33, may finally know herself better, she doesn’t seem to know her audience as well. A good portion of the 9,000 fans were girls under the age of 14 — even under 10 — and asking them to sit through three opening acts is not prudent. Clarkson didn’t hit the stage until almost 9:30 p.m. — 2½ hours after the concert began.

With all due respect to newcomer Abi Ann and pop-rocker Eric Hutchinson and his band of Minnesotans, Pentatonix, the a cappella champs from TV’s “The Sing-Off,” was all Clarkson needed. Not only were they aca-awesome with their imaginative medleys of Michael Jackson and Daft Punk and stunning reading of Imogen Heap’s “A-ha,” but they perked up Clarkson’s recent hit “Heartbeat Song” during her set.

It’s important to know thine audience as well as thyself.