Career
Gregerson was appointed to the state legislature on December 16, 2013 by the King County Council, despite being the second choice of the Democratic Precinct Committee Officers from the district. 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. In 2007, she was first elected, without opposition, to the SeaTac City Council.
In 2011, Gregerson held onto her seat on the council by a slim 31 vote margin against newcomer Erin Sitterley.
In a 2015 re-match Gregerson lost her re-election campaign for SeaTac City Council Position 7 with 40.90% of the votes (1512 votes). In her 2015 re-election campaign for SeaTac City Council position 7, Mia Gregerson falsely claimed cr for a city park cleanup project which she voted against.
Council member Pam Fernald was responsible for getting the North SeaTac Park cleaned up.