Despite it being Super Bowl Sunday and pouring rain, Rex Orange County was still met with a line of fans waiting outside the Music Hall of Williamsburg — where he made his debut in the United States.  Rex Orange County is the stage name for Alex O’Connor. At only 19-years-old, O’Connor — whose music seamlessly spans multiple genres from indie pop rock to hip-hop and soul — is quickly making a name for himself in the industry.

Within the past year, Rex Orange County has rocketed to acclaim and popularity. He has collaborated with BadBadNotGood as well as Tyler, The Creator. His vocals were featured in “Boredom” off Tyler’s recent album “Flower Boy.” In April, he released his sophomore studio album, “Apricot Princess,” and his October single release “Loving Is Easy” has shot up to more than 10 million listens on Spotify in the past three months to become his most popular track on the streaming service.

Louisiana-based artist Zack Villere kicked off the night with his unique brand of lo-fi rhythm and blues music and promptly snuck into the crowd for the main event. Then, Rex Orange County fittingly began his set with “Rex (Intro),” the introduction to his first album “Bcos U Will Never Be Free.” He mixed together songs from both of his albums as well as some of his singles, which appealed to fans both old and new. Rex played faster and upbeat songs like “Sunflower” and “Uno” back-to-back with slower, more ballad-like songs such as “Untitled” and “A Song About Being Sad.” His lyrics, both deeply personal and self-aware with distinctive phrasing, were easily shouted back at him by a crowd of more than 500 fans.

Rex switched deftly from guitar to keyboard and back again, all while proving his command on vocals, which sounded just as clear and strong as on the recordings — if not better. He performed some songs solo, others with his band and some with the addition of a live horns section. His casual and fun energy reverberated throughout the venue, as did his gratitude. During the very first song, Rex acknowledged how appreciative he was of the crowd and established that he was ready to have a fun night with them. He also dedicated several songs to his girlfriend, Thea, who stood on the balcony and sings with him on “Sycamore Girl” with lyrics like, “And I want you to love me the way you love your family, the way you love to show me what it’s like to be happy” from “Happiness.”

Just as he began with the introduction to his first album, Rex closed out the night with the conclusion to “Apricot Princess,” “Happiness.” His appreciation for the fans showed in this final performance, the lyrics and musical arrangement culminating in a raucous fusion of electric guitar, horns and piano — just as brightly colored balloons rained down on the audience like confetti, ending the show on the perfect note.

Email Jillian Harrington at [email protected].