"Without you, no one knows what would have become of him", the president said.
Mamoudou Gassama took just 40 seconds to scale the outside of the building.The family of the boy Mr Gassama rescued have thanked him. Paris Mayor Anne Hidalgo also praised Gassama's heroism and said she had called him to thank him. I didn't think about the floors. "I went out, I ran to look at the solutions to save him, I managed to catch the balcony, I climbed like this and thank God I saved him".
Gassama's actions have impressed many of Paris's citizens, including President Macron.
Macron, who had been criticised by left-wing voters for taking a tougher stance on immigration since his election, may also have sought to send a message to Socialist voters by signalling a more welcoming attitude to a deserving migrant.
"There's a general feeling of shameful political exploitation", said Jean-Claude Mas, secretary general of La Cimade, which defends migrants.
The young man said he has papers to legally stay in Italy, where he arrived in Europe after crossing the Mediterranean, ending a long, rough stay in Libya.
A man on the fourth floor was leaning across another balcony struggling to hold on to the child. The video below, in case you haven't seen it yet, shows Gassama scaling several stories without any kind of gear or precautions to assist him.
The Parisian fire service said crews had arrived to find the boy had already been rescued. He came to France in September to join his older brother, who has lived in France for decades.
"I saved the child and then went inside the building and I was shaking", he told Macron.
"I told him that his heroic act is an example to all citizens and that the city of Paris will obviously be very keen to support him in his efforts to settle in France", she added.
Mr Gassama has been hailed a hero and has been offered French citizenship.
A young Malian employee, Lassana Bathily, was credited with saving the lives of six hostages including a baby when he led them to a safe hiding place, escaped, then directed gendarmes to their rescue.
Macron is behind a bill toughening French immigration law, and he stressed there is no contradiction between rewarding Gassama for his act of bravery and working to prevent migrants from entering France illegally by stopping the stream of arrivals at its source.
Across the political class Gassama received plaudits.