The 100-foot-tall ship, which has been in use for over four decades, is equipped with 1,000 beds and 12 operating rooms.
"All patient transfers will be coordinated with local hospitals, thus ensuring a consistent handoff of care between medical provider", according to the Navy.
"It's a wartime atmosphere and we all have to pull together", Mr de Blasio said after the ship's arrival.
Many prominent government figures have praised the decision to deploy the ship in New York City, which has become the U.S.'s epicenter for the outbreak of the novel coronavirus.
The ship was sent as part of President Donald Trump's federal response to the coronavirus pandemic. The ship will alleviate the stress on hospitals, allowing them to devote more of their time and resources to COVID-19 patients.
The ship's arrival comes as NY state's death toll from the coronavirus outbreak climbed Sunday above 1,000, less than a month after the first known infection in the state.
In California, another hard-hit state, Governor Gavin Newsom said the number of Covid-19 hospitalisations had almost doubled over the past four days and the number of ICU patients had tripled.
The USNS Comfort passes the Statue of Liberty as it enters New York Harbor during the outbreak of the coronavirus disease (COVID-19) in New York City, U.S., March 30, 2020. "The hospital capacity we add now will save lives".
De Blasio said the death toll in his city would rise if Washington did not provide more assistance soon.
"This ship represents all that is good about the American people".
"If we do things together well - nearly perfectly - we could get in the range of 100,000 to 200,000 fatalities", Dr Deborah Birx, coordinator of the White House's coronavirus task force, told NBC's "Today" show.
The beds were scheduled to be set up around the courts, with construction of the pop-up hospital starting Tuesday. We need all the help we can get here in New York City and to know our military is here to help us. "A lot of these deaths are already percolating", said Dana Miller, 61, of Belmont, Massachusetts, a retired health policy official in the U.S. government. The mayor says those parks will be locked with signs put up and enforcement to prevent people from getting in.
Wen said in the Baltimore area, "this is still the relative calm before the storm but we know that storm is not far away because we are hearing and seeing the reports of our colleagues in NY".