A Democrat, Gregerson has served as a member of the Washington House of Representatives from the 33rd Legislative District since 2013.

[2][3] Professionally, Gregerson has worked as a surgical assistant and as a business manager in the dental industry.

[7] Gregerson was appointed to the state legislature on December 16, 2013, as the preferred candidate of the King County Council, one of three recommended by the 33rd Legislative District Democratic Precinct Committee Officers.

[8][9][10] Gregerson filled the vacancy left after Dave Upthegrove resigned from his seat in the legislature on December 16, 2013, following his election to the King County Council.

[13] Gregerson cosponsored legislation that would legalize the building of accessory dwelling units (ADU) in urban growth areas to alleviate the state's housing shortage.