The Canadian was set to be the top seed at the WTA International tournament played on hard courts in Washington.
But tournament officials were told of the 20-year-old's withdrawal on Thursday, with no particular injury specified.
Jeff Newman, the tournament director, wished Bouchard well, but is still pleased with the quality in the women's draw.
"It goes without saying that we would have loved to see Genie play for our fans, but first and foremost, we wish her a speedy recovery," he said in a statement.
"As always, the tournament has never been about one particular player but the strength and depth of the fields as a whole.
"Having five top-10 players in the draws will make for an exciting week of world-class tennis."