This would be Castro's first trip to the United States as president, though it's not clear what else he has planned.
An updated UN list of speakers notes that the Cuban head of state will speak at the gathering on Sept 28, the same day that President Barack Obama is set to speak.
Diplomats for the two countries last week formally launched the process of normalizing the US-Cuba relationship, one of the top foreign policy achievements of Obama's presidency.
A spokesman for Cuba's mission to the UN did not comment today on Castro's expected visit and only referred to the UN list of speakers.
Castro first will play host as Pope Francis visits Cuba from Sept 19-22, ahead of Francis' own first trip to the United States.
More than 160 heads of state and government are set to attend this month's UN meeting, including Chinese President Xi Jinping for the first time. Russian President Vladimir Putin and Iranian President Hassan Rouhani are also among the first day's speakers.