Reporters and editors at the commonly owned New York news sites DNAinfo and Gothamist are now represented by a union.

The newsroom workers initially agreed to join the union, the Writers Guild of America East, in April, shortly after DNAinfo bought Gothamist. But DNAinfo’s owner, Joe Ricketts, refused to recognize the union, so the National Labor Relations Board conducted a formal vote on Thursday. The result — 25 out of 27 workers voted to join the Writers Guild — means that management is required to bargain with the union.

DNAinfo, which specializes in covering the city neighborhood by neighborhood, has broken big stories and earned respect since its founding in 2009, but it has never turned a profit. Gothamist, with a smaller staff but wider readership, is a blog with attitude that combines original reporting, cultural coverage and aggregation.

After the workers tried to organize in the spring, Mr. Ricketts, who founded TD Ameritrade and whose family owns the Chicago Cubs, wrote to them, “As long as it’s my money that’s paying for everything, I intend to be the one making the decisions about the direction of the business.”