By Paul Robicheau

For all the teen-pop trappings, however, there is an old-fashioned sensibility to Rex Orange County’s music.

Rex Orange County at the House of Blues Boston. Photo: Paul Robicheau.

More than just today’s home-based version of DIY recording, bedroom pop lets musicians settle into their own world with more personal, introspective results. And few musicians wear a heart on their sleeve as much as English upstart Rex Orange County, the stage name of 21-year-old Alexander O’Connor, whose sold-out show at House of Blues on Tuesday proved an awkward if endearing love-in.

Rex came across as that geeky, adorable guy that both teenaged girls and their parents can embrace, like a gap-toothed Ferris Bueller. Hey, you can’t appear more squeaky-clean than taking the stage wearing a T-shirt from the Ellen DeGeneres Show to inspire giddy sing-alongs to songs about self-doubt and young romance.

He was high-energy smiles to start, bouncing from an electric piano to grab a mic and spin around the stage like a loose-limbed cheerleader in “10/10.” Then the singer shifted to a capable rap cadence on “Laser Lights,” reminding us how he once collaborated with hip-hop star Tyler, the Creator. And when Rex finally strapped on an electric guitar to rock the tumbling emotions of “Never Enough,” his backing quintet — featuring crisp drums and two horns — kicked it higher.

Still, Rex remained a crooner for much of the 100-minute show. He wasn’t always on pitch in balladeer mode, though he didn’t show evidence of the illness that led him to scrap a Monday date at House of Blues (he apologized on Tuesday, but a separate full slate of fans were left waiting for a yet-to-be-announced remake).

Rex Orange County at the House of Blues Boston. Photo: Paul Robicheau.

A curtain dropped behind Rex, cuing a four-song solo stretch at mid-set, starting at the keyboard to croon “Every Way,” which sweetly began “I care about you in every way I can.” And he even navigated a cover of Alicia Keys’ “No One,” prompting at least as much of a sing-along as his own songs had garnered.

The curtain eventually fell, confetti canons erupted, mirror balls replaced clouds on poles, and a giant inflatable pony appeared for “Never Had the Balls.” But it was older favorite “Best Friend”—stuffed with cozy lines like “I’ll be your biggest fan and you’ll be mine”—that exploded with energy when the singer asked the crowd to ditch cellphones for an inclusive moment and fans danced and shouted along in a frothy sea of joy. It was impossible to top that moment, though Rex kept rolling for a few more songs, an encore of “Always” positioned for him to impart “You’ll always be a part of me.”

For all the teen-pop trappings, however, there was an old-fashioned sensibility to Rex’s music, from his crooning persona to sing-songy melodies to instrumentation laced with jazz (including horn solos in “Sunshine”) and a country twang to his simple guitar notes in “Corduroy Dreams.” On a stage covered with flower-sprinkled fake grass like a miniature golf course, Rex shared plenty of familiar dreams.

Paul Robicheau served as the contributing editor for music in The Improper Bostonian in addition to writing and photography for The Boston Globe, Rolling Stone and other publications.