"The mayor will depart this evening for Berlin and Hamburg, Germany. He will attend several events surrounding the G20. [D]etails to follow," Phillips tweeted.
It was unclear whether De Blasio would be participating in any meetings or events at the summit.
De Blasio, a Democrat, has been an ardent critic of President Donald Trump, particularly on the issue of climate change.
The New York politician was among 343 mayors who pledged to uphold the goals of the Paris climate accord after Trump announced that the United States would withdraw from the landmark international agreement.
Climate change is expected to be among the top issues on the agenda at the G20 summit.