Before her election to the Senate in November 2018, Sen. Danielson served in the Colorado State House from 2015 to 2018, where she represented District 24. In her second term as a state representative, she served as Speaker Pro Tem. While in the Colorado House, Sen. Danielson was a leader on equal pay for equal work, fighting elder abuse, getting rid of red tape for veterans looking for a job or college degree, and cracking down on wage theft. She also sponsored the bill that legalized rain barrels for Colorado homeowners.

Before serving in elected office, Jessie was the Colorado State Director for America Votes, which works nationwide to expand access to the ballot and protect every American citizen's right to vote. Her work there was instrumental in the passage of the groundbreaking Voter Access & Modernized Elections Act of 2013, which has expanded every Coloradan's access to the ballot. Prior to America Votes, Sen. Danielson worked as Political Director for NARAL Pro-Choice Colorado, overseeing its electoral strategy, legislative outreach, and grassroots organizing programs. She was also a housing coordinator for Connections for Independent Living, a nonprofit organization that helps individuals with disabilities lead full and independent lives.

Sen. Danielson is a former chair of the board of directors for Emerge Colorado and a former board member of both NARAL Pro-Choice Colorado and ProgressNow Colorado. She has served as a gubernatorial appointee on both the Colorado Commission on Aging and the Voter Access & Modernized Elections Commission.

A fifth-generation Coloradan, Sen. Danielson grew up on her family's farm near Ault in Weld County. She earned a bachelor's degree from the University of Colorado Boulder. She and her husband, Andy, live in Wheat Ridge with their daughter.