Akayed Ullah, a 27-year-old immigrant from Bangladesh, recalled a Christmas attack in Europe in 2016 and said he was also retaliating for US airstrikes on IS in Syria, law enforcement officials told the New York Times.
The bomb, set off in a crowded subway passage during the morning rush hour, only partially detonated, deeply wounding the bomber himself but only causing slight injuries to three other people.
Ullah was burned on his torso and hands and was taken to hospital where he was said to be in serious condition.
The mention of Christmas as a motive drew comparisons to Europe, where an IS-inspired attacker plowed a truck into a Berlin Christmas market last year, killing 12 people.

Photo provided by the New York City Taxi and Limousine Commission shows Akayed Ullah, the suspect in the explosion near New York's Times Square on Dec 11, 2017. Source: NY Taxi and Limousine Commission
US authorities have warned travelers to Europe during the holiday season to beware of possible attacks on popular gathering places and travel hubs.
Three other people were also hurt in the blast in a pedestrian tunnel linking two subway stops beneath West 42nd Street, officials said.
One neighbor in the Brooklyn neighborhood of Windsor Terrace said she had not seen him in months but described his home as quiet and observant in Islamic customs. She saw no evidence of extremism.
“They’re really nice people. This is shocking,” said the neighbor, Arlene Jograj, a teacher who had greeted Ullah in passing. “We all know each other. We have block parties. I’ve been over there for dinner parties after Ramadan. We’re a really tight-knit street,” she said.
Ullah came from the southeastern Bangladeshi district of Chittagong and last visited the country on September 8, Inspector General of Police A K M Shahidul Hoque told Reuters on Monday.

This is a photo believed to be of the New York bomber suspect. Source: Twitter: New York City Alerts
Several US officials familiar with the investigation told Reuters there was no information indicating Ullah was previously known to any US spy or law enforcement agency for any connection to militant groups. But that does not rule out the possibility some connection could be found.
Ullah arrived in the United States seven years ago on a family visa, one authoritative US source said, speaking on condition of anonymity.
Ullah also had no criminal record in his home country which he last visited in September, Bangladesh’s police chief said on Monday.
Bangladesh's Inspector General of Police A K M Shahidul Hoque told Reuters the information that he had no criminal record in his home country was based on the passport number of the suspect, Akayed Ullah.
Ullah had a black cab/limousine driver’s license from 2012 to 2015, the New York Taxi and Limousine Commission said.
The Bangladeshi government also issued a statement on Monday condemning the attack.
“A terrorist is a terrorist irrespective of his or her ethnicity or religion, and must be brought to justice,” a spokesman for the country’s embassy in Washington said in an emailed statement.
Ullah, who had a homemade bomb strapped to his body, set off an explosion in an underground pedestrian corridor between New York’s Times Square and the Port Authority Bus Terminal at rush hour, injuring himself and three others in what New York Mayor Bill de Blasio called an attempted terrorist attack.
He had burns and lacerations while the three other people, including a police officer, had minor injuries.
Ullah was influenced by violent Islamist extremists and was “angry,” New York state Governor Andrew Cuomo said. This could have been for any number of reasons, whether because of US policy abroad or his lot in life at home, he said.