An $850 million project to build a glitzy new plaza surrounded by apartments, offices, shops and a new YMCA on a municipal parking lot in Queens won a key approval yesterday from city planners.

The Planning Commission’s 10-1 vote leaves just one hurdle — approval by the City Council — before construction of the project in downtown Flushing.

“The transformation of an underutilized five-acre parking lot into a mixed-use urban center will establish a new center of activity for this vibrant community,” Mayor Bloomberg said.

Flushing Commons would include 600 upscale condos, as well as a hotel, offices and shops.