The new 22,000 square foot "Perelman Emergency Center" is said to have the newest technologies in emergency medicine.
The hospital had to be evacuated during the storm when it became flooded, and both power systems failed.
The new facility will more than triple the size of the old emergency department.
The Manhattan hospital launched an urgent care center after Sandy to help handle needs.
The new facility will include more treatment rooms, plus dedicated space for pediatric emergencies.
The storm flooded and forced the closure of some of the city's biggest hospitals.
Millions of gallons of water poured into the lower levels of Bellevue Hospital , Coney Island Hospital and NYU Langone, destroying medical and electrical equipment, and the fuel for emergency generators.
In total, medical teams safely evacuated over 6,000 patients from 37 healthcare facilities.