DeGraw made the announcement Sunday on her campaign's Facebook page.
The announcement comes a month and a half before the first day candidates can officially file to run for positions in the 2018 election. The first day to file is Sept. 7.
DeGraw, the Northwest Senior Organizer for the environmental advocacy organization Food & Water Watch, is running on a platform of environmental stewardship and fair housing practices.
She also notes she would be the only city commissioner to live east of 82nd Avenue, a historically underrepresented area in Portland politics.
"Business as usual politics isn't working for the people of Portland," she said. "The east side of our city lacks representation, if elected I would be the only City Commissioner East of Cesar Chavez Blvd. I am committed to work with and for the people of Portland to make this city better for everyone."
While Oregon native DeGraw has never held political office, she has experience lobbying for causes. She was vocal in the fight against the Nestle water bottling plant in Cascade Locks and keeping fracking gas from traveling through the state.
Fish has been a city commissioner since 2008. The 58-year-old Harvard and Northeastern University graduate and former civil rights lawyer headed the Portland Housing Bureau and Portland Parks and Recreation for four years. He currently oversees the Portland Water Bureau and the Bureau of Environmental Services. He has lived in Portland since 1996.
In 2014, he easily won reelection during the primary election with 73 percent of the vote.
Fish is currently in Washington D.C. to brief the congressional delegation on Portland's effort to clean up the Portland Harbor Superfund Site. He said he's looking forward to a spirited race.
"It's very early but I expect a lot of good people will get into these races and I look forward to talking about my record and my positive vision for Portland's future," he said.
Fish has raised more than $28,000 for his 2018 city council campaign since he won reelection in May 2014. He is planning a formal campaign kickoff this fall.
DeGraw does not yet have donations on record with the Oregon Secretary of State’s office. She said her campaign will not accept corporate contributions.
The 2018 primary election is May 15. If no candidate gets more than 50 percent of the vote, the top two move on to the November 6 general election.
City Commissioner Dan Saltzman and City Auditor Mary Hull Caballero are also up for reelection in 2018.