The pregnant princess, who was a guest of Ban Soon-Taek, the wife of the Secretary-General of the United Nations, sported a pale blue dress, a matching jacket and silver heels.
Throughout the conference, Charlene was seen chatting with Autism Speaks founder Suzanne Wright, pausing occasionally to tenderly touch her baby bump.
Left to right: Ban Soon-Taek, Princess Charlene of Monaco and Suzanne Wright
Charlene beamed as she toured the room, engaging with numerous women involved with the charity.
Is Princess Charlene of Monaco pregnant with twins?
Thursday's outing was one of a number that Charlene has made during her time in the Big Apple with Prince Albert.
Princess Charlene speaking to fellow first-time mum-to-be Chelsea Clinton
On Monday, the former Olympic swimmer was spotted deep in conversation with fellow mum-to-be Chelsea Clinton at the 10th Annual Meeting of the Clinton Global Initiative at the Sheraton hotel.
The following day, Monaco's reigning couple met with US president Barack Obama and his wife Michelle.
Charlene wore a sleeveless black and white dress for a reception hosted by America's first couple to mark the Summit of Heads of State to discuss climate change at the United Nations.
Albert and Charlene with Barrack and Michelle Obama
Zimbabwe-born Charlene's trip to New York is her first official overseas visit since she announced the news of her pregnancy in May.
Pregnant Princess Charlene shines at open-air concert with Prince Albert
"T.S.H the Prince and the Princess of Monaco are delighted to announce the pregnancy of H.S.H. Princess Charlene," read an announcement released by the Palace of Monaco. "The birth is expected at the end of the year."