After the UN's  adoption of the Convention for the Prevention and Punishment of the Crime of Genocide in 1948, Lemkin became a celebrity. Many newspaper articles were written about him and he was even nominated twice for a Nobel Peace Prize. He received the Grand Cross of Cespedes from Cuba in 1950 and the Stephen Wise Award of the American Jewish Congress in 1951.

He became a lecturer at Yale, and also taught at Rutgers and Princeton, but he continued his work on genocide. He consulted for the UN, played a leading role in the U.S. Committee for a UN Genocide Convention, and drafted a manuscript, History of Genocide, which, however, was never published.

But Lemkin's celebrity was short-lived. By the time he died of a heart attack on August 28, 1959, he was poverty-stricken and alone. His funeral was attended by only a few people.

The headstone on his grave at Mt. Hebron Cemetery in Queens reads "The Father of the Genocide Convention."

But, despite Lemkin’s unflagging efforts to outlaw genocide, the crime continues.  In the last two decades, the Convention on the Prevention and Punishment of the Crime of Genocide has been implemented as a basis for prosecution and judgment in former Yugoslavia, against those responsible for genocidal acts against Muslims in Bosnia-Herzegovina, and in Rwanda, where genocide was perpetrated against the Tutsi minority by members of the Hutu Interhamwe militia and collaborators.