Businesses are bracing for Monday’s delivery doomsday when the de Blasio administration bans curbside drop-offs in parts of the city to curb congestion.

“It will completely disrupt the way the supermarket operates,” said Marko Lalic, co-owner of a new Union Market at 342 Flatbush Ave.

Starting Monday, in a pilot program, the city will ban curbside deliveries between 7 and 10 a.m. and 4 to 7 p.m. along Flatbush Avenue in Brooklyn and Roosevelt Avenue in Queens.

The ban will expand to parts of Midtown on April 2.