Vignarajah, 37, of Gaithersburg, will compete against Prince George's County Executive Rushern L. Baker III, former NAACP president Ben Jealous, state Sen. Richard S. Madaleno Jr. (D-Montgomery), technology entrepreneur Alec Ross and lawyer James L. Shea.
Baltimore County Executive Kevin B. Kamenetz, former Maryland attorney general Douglas F. Gansler and Maya Rockeymoore, a policy consultant who is married to U.S. Rep. Elijah E. Cummings (D-Md.), also have said they are considering the race.
Last month, U.S. Rep. John Delaney opted out of the race and announced plans to run for president.
No woman holds any of Maryland's four statewide elected executive positions. And since the retirement of longtime U.S. senator Barbara A. Mikulski (D), the state has no women serving in its congressional delegation — a first in 76 years.
Shortly after Vignarajah's announcement, questions were raised by an opposing campaign about whether she is actually eligible to run for governor.
Under the state constitution, a person must be at least 30 years old, and both a Maryland resident and registered voter for five years immediately prior to election.
Vignarajah is registered in both the District and Maryland. She registered in Maryland in 2006 and in the District in 2010, according to voting records.
She voted in the District in 2014 and voted in Maryland in 2016. She also has residences in both locations.
Vignarajah said her mother helped her buy an apartment in the District when she was working a hectic schedule working for the Obama administration.
"It was never my permanent residence," she said of the apartment. "The Catonsville address was my home."
Vignarajah said she was not unlike many members of the Obama administration, who had residences in the District and in their home states.
She said she was disappointed to learn about the questions surrounding her eligibility to serve.
"This kind of attack is no better than Trump's questions on President Obama's citizenship," Vignarajah said.
If elected, Vignarajah plans to focus on "improving schools, increasing wages, reducing crime, treating drug addiction, alleviating traffic, investing in infrastructure and protecting our treasured environment."
She said Gov. Larry Hogan (R) has offered a "deficit in leadership," failing to move Maryland in the right direction in job creation, school performance and conservation.
"Today too many of the students who can least afford to be left behind have been forgotten altogether," she said. "Too many workers have been left out. And our precious Chesapeake Bay faces its greatest risks in decades."
Hannah Mar, a spokeswoman for Hogan, said the governor's policies have created more than 106,000 jobs, provided "historic levels" of education funding and taken "unprecedented" actions to protect the Chesapeake Bay.
Before her work for Obama, Vignarajah worked at the State Department as a senior adviser under Hillary Clinton and John F. Kerry.
The daughter of Baltimore City schoolteachers, Vignarajah grew up in Baltimore County after her parents moved to the United States from Sri Lanka. She received degrees from Yale College and Yale Law School.
Before joining the Obama administration, she worked at McKinsey & Co., a New York-based consulting firm, and Jenner & Block, a Chicago-based law firm. She also taught at Georgetown University.