RNA - Demonstrators waved placards that read, "Justice for Jamal" outside a luxury venue in downtown Manhattan where MbS' Misk Foundation was holding a workshop for entrepreneurs, called the Misk Youth Forum, Al-Jazeera reported.
Activists blasted the event as an effort to rehabilitate the image of MbS following the October 2, 2018, murder of Khashoggi.
"It's not even been a year since a US resident, Saudi dissident and journalist was lured out of the United States and in a premeditated and brazen way, murdered," Rob Berschinski, a policy chief for the campaign group Human Rights First, told Al-Jazeera outside the venue.
Khashoggi was killed and his body dismembered after he entered the Saudi consulate in Istanbul, Turkey, to collect documents related to his planned wedding.
After initially offering contradictory statements, Saudi Arabia confirmed its agents killed Khashoggi, but denied its senior leaders were involved.
US intelligence agencies have reportedly concluded, however, that MbS ordered the murder, and a UN right expert found "credible evidence" linking the Crown Prince to the killing, allegations the kingdom denies.
"Those who, according to US and UN investigators were behind that murder, should not be allowed to rehabilitate their reputations in the way that this event and others organised by the Misk Foundation are clearly geared towards," Berschinski added.
The Misk Foundation declined to comment and did not grant Al-Jazeera access to the event.
Controversy dogged Monday's event from the outset. More than 7,000 people signed an online petition, calling for the event to be cancelled.
"Step by step, we are going to shut down the Saudi dictatorship's propaganda machine in the US," said Sunjeev Bery, director of the anti-autocrat campaign group Freedom Forward, who organised the petition.
"No public institution or private business should be helping the Saudi dictatorship in any way with its efforts to wash away its crimes in Yemen, its imprisonment of activists, and its murder of Jamal Khashoggi," he told Al-Jazeera.
Event planners had to switch venues after the New York Public Library cancelled the foundation's reservation, citing "concerns about possible disruption to Library operations as well as the safety of our patrons".
This week, the co-host, United Nations youth envoy Jayathma Wickramanayake, pulled out.
"The youth envoy has decided to withdraw because, under the current environment, her participation to the forum would not bring the outcomes we had originally wished for: to bring together young leaders, influencers, creators and innovators to take on the challenge of change and contribute to UN goals," a UN Spokesman told Al-Jazeera.
Joyce Bukuru, an advocacy officer for the campaign group Human Rights Watch, said that the UN should never have gotten involved with a foundation that is run by MbS.
"The UN has made the right call by pulling out of a joint event with the Saudi crown prince's private organization on the eve of the one-year anniversary of Khashoggi's gruesome murder," Bukuru told Al-Jazeera.
"Next time, it should think twice before agreeing to lend its credibility to the Saudi government's attempts at whitewashing its dismal human rights record," he added.
Two speakers originally set to attend - Ann Rosenberg, a technology executive, and Bart Houlahan, a business consultant - also decided they would not take part in the forum, amid concerns over the Misk Foundation.
The five-hour workshop for young adults took place on the sidelines of the UN General Assembly and promoted green themes, corporate responsibility and other aspects of the UN's Sustainable Development Goal (SDG) agenda.
It remains unclear whether the 300 participants who were originally set to attend made it to the new venue.
At the start time, only a small number of guests appeared to be entering the premises.
Mohammad Alshatwi, a mechanical engineering student at Bridgeport University, spoke with Al- Jazeera briefly outside the venue, saying he had travelled from Connecticut to New York to attend.
"I didn't come here to talk about politics," said Alshatwi, stating, "I came here because Misk does valuable work for your people."
"These protesters are not here because of human rights, they are here because somebody paid them to be here," he added, without offering evidence.