He sang the song with the Naturally 7 a capella group as subway riders watched. He then uploaded a video of the brief concert to YouTube.
The song, whose most famous rendition was done by the Jackson 5, is one of the tracks on Buble's latest album, "To Be Loved," released Tuesday.
"Singing in the New York subway is something that's been done for years and years and years, and I feel like it's the most authentic, organic way to make music," he said from the 66th Street platform.
He didn't mention Lincoln Center's Avery Fisher Hall, David H. Koch Theater and Metropolitan Opera House, but said the subway station's tiled walls made for good acoustics.
"You see some of the greatest musicians come down here and play," he said in the video.
"Out of all the press I had to do -- out of everything that I'm going to do in Europe and America -- this was the thing I was most excited about," he said.
"To Be Loved," recorded in Vancouver, British Columbia, and Los Angeles, includes 10 standards, and four original songs co-written by Buble.
The album features appearances by actress Reese Witherspoon, Naturally 7 and the Puppini Sisters close-harmony vocal trio.