Ecstatic Livies, the title singer-songwriter Olivia Rodrigo’s most ardent fans proudly brandish, swarmed TD Garden April 1 with everything from jewel-encrusted cowgirl hats to flowy ribbons atop their heads for the “GUTS World Tour.”

Rodrigo, the latest in a long lineage of Disney-Channel-stars-turned-pop-sensations, arrived in Boston on the heels of the success of her sophomore effort, “GUTS,” which garnered widespread acclaim and nominations for six Grammy Awards, including Album of the Year.

Joining the 21-year-old “drivers license” singer for this tour stop was Chappell Roan, the ever-eccentric, campily captivating performer behind last year’s “The Rise and Fall of a Midwest Princess” and a recently-released Tiny Desk Concert for the ages.

Roan, the show’s opener, took the stage at 7:30 p.m. in a shimmering, cerulean ensemble, with a radiant neon sign proclaiming “Chappell Roan” hanging above her at center stage.

She playfully pranced about the stage, jumping, kicking and headbanging with fervor, her auburn hair in constant motion. The high-octane performance greatly resonated with attendees, evidenced by shrill screams and enthusiastic dancing — especially during tracks like “HOT TO GO!”

Before starting the upbeat number, though, Roan had a question for her enraptured audience.

“Can I teach you a dance?” she coyly inquired. “It’s like the YMCA, but harder.”

Roan taught the crowd some simple choreography, demonstrating how to spell the song’s title, letter by letter, with arms alone. She even gave them a chance to practice the dance down-tempo. “H-O-T-T-O-G-O / You can take me hot to go,” she sang slowly, audience members doing their best to move their arms accordingly.

“Ok, three of you got it,” Roan joked, earning hoots and hollers as she began in earnest.

Roan’s TikTok-viral song “Casual,” a moody ballad about the heartache associated with having a partner who views the relationship as less than it actually is, similarly ensnared the audience. What was once an elated group of spectators, though, turned mournful, undoubtedly relating to Roan’s melancholic lyrics, which they sang with unbridled tenacity.

After thanking the attendees and Rodrigo, Roan departed the stage — one emotional rollercoaster down, one more to go.

Preceding Rodrigo’s set was a black-and-white, pre-recorded video in which the “High School Musical: The Musical: The Series” alum frantically traversed backstage before happening upon a purple door. She knocked on it — as she does at the onset of “bad idea right?” — before bursting on stage, and the Livies’ thunderous applause and guttural yells all but broke the sound barrier.

In a glistening silver getup, Rodrigo moved about the stage, singing the lyrics from the aforementioned track before taking a page out of Beyoncé’s book.

Beyoncé conceived the “Everybody on Mute” challenge for last year’s “Renaissance World Tour,” one in which Beyhive members were meant to go quiet when, during the superstar’s rendition of “ENERGY,” she sang, “Look around, everybody on mute.” 

Rodrigo achieved something similar, going silent — and hoping that the audience would, too — mid-lyric: “Now I’m gettin’ in the car, wreckin’ all my plans / I know I should stop-, but I can’t.” 

Following this, Rodrigo performed “ballad of a homeschooled girl,” the screen behind her featuring a yearbook design in which live concert footage replaced the spaces where students’ headshots are usually located, making for a visually unique backdrop.

The night’s best use of the screens, though, inarguably came during “teenage dream,” a heart-wrenching piece concerning the mixed emotions leaving your adolescence behind brings forth. Throughout the song, Rodrigo’s archival home video footage, in which, as a child, she danced ballet, attended kindergarten graduation and belted into a microphone, populated TD Garden’s mainstage screen. This, in conjunction with the track’s somber lyrics, culminated in an emotionally riveting performance that brought many to tears.

Rodrigo’s slower songs, like “teenage dream,” “traitor” and “making the bed,” all additionally showcased her immense vocal talent. She hit high notes with ease and clarity, never failing to enunciate even while at the top of her register. Her voice also blended perfectly with her background singers, especially during the harmony-heavy “Can’t Catch Me Now,” a song Rodrigo co-wrote with frequent collaborator Dan Nigro for “The Hunger Games: The Ballad of Songbirds and Snakes.” 

Beyond her vocals, Rodrigo impressed with her theatrics, stomping around the stage and releasing pent-up frustration during “brutal,” making for a truly cathartic moment. She similarly channeled her emotions into an explosive rendition of “jealousy, jealousy,” scaling the pit’s surrounding barricade to sing to and interact with her adoring fans.

Rodrigo, formerly on the Mouse’s payroll, further used the concert as an opportunity to shed the good-girl image she acquired while working on shows like “Bizaardvark.” During “obsessed,” for instance, she seductively crawled about a transparent floor, bathed in red light, a camera underneath capturing her figure in its entirety.

After “get him back!” — the final encore number — concluded and multicolored confetti cascaded from the ceiling, Rodrigo abandoned her microphone and returned to the pit’s boundaries, high-fiving concertgoers and accepting the bracelets and trinkets they made just for her. 

She then turned to a nearby camera, its live footage filling the mainstage screen once again, and mouthed “Thank you for coming!” and “I love you!” before finally departing the arena.

If the Livie’s raucous response was any indication, the feeling was mutual — and, having been there, it’s easy to ascertain why.