The independent was defeated in November by independent David Grosso.
The D.C. Board of Elections says Mr. Brown picked up nominating petitions Wednesday for a special election in April. He has three weeks to collect 3,000 signatures from registered D.C. voters in order to appear on the ballot.
Mr. Brown was elected in 2008 to a seat reserved for members of non-majority parties. Now there’s another at-large seat open, the seat once occupied by Phil Mendelson. Mr. Mendelson is now D.C. Council chairman and Mr. Brown has changed his registration back to the Democratic Party to run for the seat.
Mr. Brown is one of 14 possible candidates who have picked up petitions.