Street signs were put up on a two-block area of 16th Street NW from K to H streets, leading directly north to the White House. The words "Black Lives Matter" were painted in yellow from curb to curb.
"The section of 16th Street in front of the White House is now officially 'Black Lives Matter Plaza,'" the mayor said in a Twitter post.
City officials said the measure was done to recognize demonstrators who have demanded changes in police practices after the death of George Floyd in police custody in Minneapolis on Memorial Day.
"There was a dispute this week about whose street it is, and Mayor Bowser wanted to make it abundantly clear whose street it is and honor the peaceful demonstrators who assembled Monday night," John Falcicchio, the mayor's chief of staff, said.
Tensions have brewed between Trump and Bowser after she complained about the use of federal law enforcement and the military response against protesters in Washington, D.C.
Rose Jaffe, one of the local artists who helped paint the huge "Black Lives Matter" street mural, said she was "conflicted" about it.
"It's about wanting to reclaim the streets, but I also know that it is a little bit of a photo op," Jaffe said. "Where is the action behind this?"