His mother was escorted to the airport by relatives and Dr Erieka Bennett, Head of Mission of the African Diaspora Forum.
“I’m going to America to plan my son’s funeral,” Gyamfi said.
She thanked the government and well-wishers for their support and prayers following her son’s death.
In a social media post on Saturday, New York mayor Zohran Mamdani said Trump had agreed to grant a visa to Gyamfi so she could mourn her son in person.
Mamdani said the murder of a child was a pain no parent should endure, “let alone from thousands of miles away.”
“Javits Frimpong’s mother deserves to say goodbye to her son in person. I just got off the phone with President Trump, and he has agreed to grant her visa immediately,” he said.
“All of New York City is mourning this tragedy,” he added.
Ghana’s government has condemned the killing and said it was following the case closely to ensure justice.
It has urged US authorities to conduct a thorough investigation and said it was ready to provide legal and consular support to ensure the perpetrators are brought to justice.
Police are searching for three teenage suspects who fled the scene, captured on surveillance footage.
The shooting has sparked concern among Ghanaians about the safety of children sent to study in America.
