"How are you doing in New York?" Modi, dressed in an off-white kurta, greeted the crowd in English after the comperes of the show, Global Citizen Festival, announced the arrival of a person who changed the sanitation facilities of the Indian state of Gujarat from one of the worst to one of the best.
"Namaste," he said, adding that he was greeting people who were watching the show on TVs, smartphones, tablets and laptops as well.
"I am truly delighted to be in an open front and not in a closed conference room."
Modi said that the work todays's youth were doing in problems like sanitation and poverty would have deep impact in the times to come.
"I salute you, I repeat, I salute you," he said as the crowd erupted in applause.
"I am proud of you, your family is proud of you, your friends are proud of you."
"In India, 800 million youth are joining hands to make drinking water and sanitaton available in the hands of everybody," he said.
Modi said that the youth in India could see that "you are joining hands" with them.
"God bless. May the force be with you," the Indian prime minister, who is visiting the US on a five-day trip and delivered his maiden speech at the UN General Assembly Saturday, concluded.