Michael Andrews, 30, was arrested Tuesday for the July 6 incident, the New York Post reported.
Police said Andrews followed Adriani Espinal and her young daughter, Destiny Maizanche, as they got onto an elevator in a Brooklyn apartment building.
"He grabbed my necklace and then he went for the baby," Espinal told the newspaper. "I told him to leave the baby alone because she was crying."
Then, Andrews grabbed Destiny's bracelet, Espinal said.
Later that same night, Andrews was allegedly involved in another robbery in a different apartment elevator, the report said. The adult victim in that incident was forced at gun point to hand over her chain necklace and cellphone.
Police said they do not believe Andrews was involved in a July 10 robbery of 3-year-old Harvey Hernandez in a apartment building entryway. In that incident, Hernandez and his mother were confronted by two men, one of whom stole the boy's chain necklace which had a medallion on it from his baptism.