When the new businesses open, they will join 21 existing vendors from the adjacent Essex Street Market, a city-run site that was set up in 1940 by the administration of Mayor Fiorello LaGuardia to take pushcarts off the streets. The Essex Street vendors are expected to move to the ground floor of the new market site this spring, while the new businesses will occupy the lower level.

Megha Chopra, assistant vice president of New York’s Economic Development Corporation, predicted that the combined market would attract regular Essex Street customers as well as new shoppers and tourists drawn by the new businesses.

“We have our own customer base that was nurtured and cultivated over the years, and a lot of those people will still come to Essex,” Ms. Chopra said. “With this development, there will also be a lot of New York City tourists or international tourists. There will be this incremental customer base coming through the market.”

The first phase of the Market Line is nearly complete. In the next phase, the space will be extended beneath two new office buildings, and the full market is expected to open in late 2020.

When fully occupied, the market will have more than 140 vendors, including new and existing tenants. The completed market will be a 150,000-square-foot space below ground that will also include galleries, art shops and a beer hall.

A few floors above, construction is proceeding on office space that will total 350,000 square feet in the two buildings. The first is expected to be complete in the summer of 2020, and the second about six months later.