2002–2006: Noise from the Basement

In 2002, Sweetnam began working with Canadian producer and instrumentalist James Robertson on what would later become Noise from the Basement, her Capitol Records/EMI debut. She recorded this album on a Shure 57 microphone. The album was recorded as demos and then it was officially mastered by producers at Capitol Records. The single "Billy S." appeared in July 2003 on the soundtrack to the movie How to Deal and quickly took off in Canada. Two more singles were released from the debut album; they fared moderately on the charts. In 2004, Sweetnam went on tour over Europe and North America as the opening act for Britney Spears on her Onyx Hotel Tour.

Sweetnam also provided the theme songs for various television shows including The Buzz on Maggie for Disney Channel, Wayside for Teletoon, and Radio Free Roscoe. She also covered "Part of Your World" from the 1989 Disney film The Little Mermaid for the compilation albums Disneymania 3 and DisneyRemixMania. In 2006, Sweetnam provided the singing voice for Barbie in The Barbie Diaries. Her songs "Girl Most Likely To", "Note to Self", "Real Life", and "This Is Me", were also included in the soundtrack to The Barbie Diaries.

2007–2008: Sound Soldier

In March 2007, Sweetnam and Rancid frontman Tim Armstrong released the single Into Action, a song written by Armstrong for Sweetnam's upcoming Sound Soldier album. The song also featured The Aggrolites. Sweetnam was the opening act for Canadian Idol winner Kalan Porter on tour.

Her album Sound Soldier was released October 30, 2007; its lead single, "Human", was nominated for a 2008 MuchMusic Video Award for Best Cinematography, but lost to Hedley's "She's So Sorry". For the second single EMI picked "(Let's Get Movin') Into Action", a rework of her previous single with Armstrong. Sweetnam directed two music videos herself for "Music Is My Boyfriend" and "Babydoll Gone Wrong". Throughout the late 2000s, she utilized MySpace to release several songs from Sound Soldier. Meanwhile, in her YouTube make-up tutorials, Sweetnam has used the songs "Rock n' Roll Baby", "Love Sugar Sweet", "Heartbreak", "Boomerang", "MuSick", and "Wolves and Witches". Sweetnam also released a song entitled "Stay", along with "Boomerang", "MuSick" and "Wolves and Witches", on her MySpace page.

Sweetnam's song "(Let's Get Movin') Into Action" was also used in an episode of the Canadian teen drama Degrassi: The Next Generation, in one deleted scene from Bandslam, and in the films Balls Out: Gary the Tennis Coach, Hotel for Dogs, and the 2010 popular film Ramona and Beezus (starring Joey King and Selena Gomez). It was also included in the soundtrack for Music from Degrassi: The Next Generation.

Sweetnam also recorded "Where I Want to Be" for Jun Senoue's album, The Works, and directed a music video for Leah Daniels' song "Northern Señorita" as well as for Ashes' song "Explode (Makes My Head)". Sweetnam also co-wrote two songs for Ashes.

2009–present: Sumo Cyco

Sweetnam began working on new music in 2009 and formed a new band, Sumo Cyco, a four-piece heavy metal and punk rock band that opened for Hollywood Undead in Toronto in April 2011. Sweetnam now went by the name Sever, which was her current alter-ego.

As of July 2012^[update], Sumo Cyco has released six singles: "Mercy", "Limp", "Interceptor", "Danger", "Loose Cannon", and a cover of Oingo Boingo's "Who Do You Want to Be?". With each new song, Sumo Cyco would direct and put together their music videos for their YouTube channel which, as of July 2022^[update], has received over seven million views.

On June 9, 2012, Sweetnam posted a video on her YouTube channel that promised that new material would eventually be released.

In April and May 2014, Sumo Cyco toured Ireland and the UK after performing at Indie Week Ireland. Then, on June 10, 2014, they released their debut album, Lost in Cyco City, in Canada.

On March 10, 2015, Sumo Cyco announced that they had signed with TKO (The Kirby Organization) Booking Agency, known for its representation of hard rock and metal acts, for worldwide representation.^[5]

Sumo Cyco released their second album, Opus Mar, in 2017.

In January 2020, the band announced they had signed a deal with Napalm Records. They released their third album, Initiation, through Napalm Records on May 7th, 2021.