On August 5, 1999, Storms signed on to play Isabella “Belle” Black on the NBC daytime drama Days of Our Lives. Although she initially faced viewers upset at the sudden SORAS aging her casting brought to the character, Storms soon was popular with the audience. Her five years on the soap opera would feature her in many high-profile storylines, such as the popular relationship with Shawn Brady, played by Jason Cook, as Storms’ character was promoted heavily as a major character within the show.

At the end of her five-year contract, Kirsten opted to not renew her contract with the series, one reason being her pilot had been picked up for the primetime show Clubhouse. Her final episode aired on July 15, 2004.

Storms returned to familiar territory on May 23, 2005, becoming the third actress to portray Mariah Maximiliana “Maxie” Jones on the ABC soap opera General Hospital. In 2008, Storms was reunited with Jason Cook, who joined the soap as Matt Hunter. She received an Emmy nomination for her role in 2009.

Storms vacated the role in fall 2011 due to medical reasons, later revealed to be endometriosis. She was temporarily replaced with Jen Lilley, and originally scheduled to return to work in February 2012. Her illness prevented her from returning on time, and Lilley was kept on for the foreseeable future. In July 2012, it was announced that Storms would return to the series. On September 5, 2012, Storms reprised the role of Maxie on-screen. Storms took maternity leave on January 2, 2014, and returned on April 8 of the same year. In March 2017 Soap Opera Spy reported that Storms was leaving Port Charles for “personal reasons,”. She returned to GH in August 2017.

It was confirmed in early 2013 that Storms was in a relationship with her former General Hospital co-star Brandon Barash. In August 2013, the couple confirmed to People that they had secretly wed in June, and were expecting their first and only child, a girl, in January 2014. On January 7, 2014, Barash confirmed on his official Twitter account that Storms had given birth to a baby girl, Harper Rose Barash. On April 6, 2016, Soap Opera Digest revealed that Storms and Barash had filed for divorce after more than two-and-a-half years of marriage citing irreconcilable differences but they will raise their daughter together as they are splitting amicably.

In 2015, Storms appeared as Selene Winterthorne in the soap opera web series Winterthorne.