Born in 1999 in Houston, Texas, Alaina Castillo is the only sister among three brothers, Adam, Micah, and David. The 22-year-old started her own YouTube channel in 2010 and posted her first public video seven years later in 2017. Since then, Castillo has posted numerous covers, songs, and vlogs.

In one of the videos, Castillo mentioned how her first cover, which was Ariana Grande’s "My Everything,” was not something she was proud of. Eventually, she had to delete it. One reason her videos started gaining more recognition was that she used ASMR while singing.

Since then, Alaina Castillo has gained a following of 800,000 subscribers on YouTube thanks to her covers of popular songs along with her own music. In the summer of 2019, Castillo hinted at releasing an EP. However, due to unknown reasons, it got postponed and was finally released in November. "I don't think I love you anymore" is the first single from her debut album, "Antisocial Butterfly," with a total of six songs. From the same album, "no importa” is her second single.

Alaina Castillo went on tour in December 2019 with just three dates across the United States to support the release of her debut album. Ever since Castillo has worked harder to release more songs of her own. In January 2020, she announced the release of her standalone single, "Valentine's Day." Only two months later, she also released "Ocean Waves."

 Her third single of 2020 was also the first single from the second album, "Just a Boy," released on 27th March 2020. However, during her December tour in 2019, she had already performed the song, stating that it would be released soon.

 During an interview with NME, Castillo revealed her second album, "The Voice Notes," set to be released on 24th April 2020. The album consisted of four tracks "Pass You By," "Just a Boy," "sad girl," and "Voicenote."

Taking after her father's language, Alaina Castillo also released a Spanish version of her album “The Voice Notes” on 22nd May 2020. Castillo has been unstoppable in her journey so far. Album after album and song after song, she has proved how age is just a number and taking a break is not an option. Just three months later, in August, Castillo released another single titled "tonight" as the lead song from her fourth project.

 Before Castillo stepped into the world of music, she also briefly worked at Subway. In one way or the other, her life has always been about being around good music and letting it define her emotions. She once revealed how she listens to Christmas music whenever she’s down as it makes her feel happy again.

 She also revealed her favorite color to be black. In her spare time, Alaina Castillo loves doing different accents, especially English accents. With the pandemic keeping everything on hold, Castillo hopes to release more songs soon and grow her fanbase through YouTube just like other big names in the industry.