De Blasio, 57, has added his name to the growing Democrats list which includes former US Vice President Joe Biden, US Senators Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts among others.
Bill de Blasio had succeeded billionaire Michael Bloomberg as the New York mayor. He tested the waters for months before announcing his decision.
Blasio is the twenty-third candidate to seek Democratic nomination to become president of the United States.
The New York Mayor has openly denounced Trump's immigration policy and has been a vocal supporter against climate change. He has personally endorsed laws aimed at protecting New York's environment.
De Blasio is married to Chirlane McCray, an African-American woman.
"I have spent a lot of time in dead last in many a poll in many a race," he told the New York Times in January.
"It's not where you start" the race that counts, he said. "It's where you end."
Bill de Blasio had succeeded billionaire Michael Bloomberg as the New York mayor.