Interior Ministry spokesman Nusrat Rahimi told The Associated Press the attacker set off explosives among the wedding participants. More than 1,000 people had been invited, one witness said.
The blast occurred near the stage where musicians were and "all the youths, children and all the people who were there were killed," witness Gul Mohammad said. One of the wounded, Mohammad Toofan, said that "a lot of guests were martyred."
"There are so many dead and wounded," said Ahmad Omid, a survivor who said about 1,200 guests had been invited to the wedding for his father's cousin. "I was with the groom in the other room when we heard the blast and then I couldn't find anyone. Everyone was lying all around the hall."
Many people in the minority Shiite Muslim Hazara ethnic group live in the part of the city where the explosion took place.
A spokesperson for a Kabul emergency hospital told Reuters 20 wounded people he been brought there. It was unclear if casualties were brought to other facilities.
Officials were not expected to release a toll until daytime Sunday. There was no immediate claim of responsibility, but both the Taliban and a local ISIS affiliate carry out bloody attacks in the capital.
Kabul's brightly lit wedding halls are known to hold hundreds of people and are a center of community life in a city weary of decades of war, with thousands of dollars spent on a single evening.
Such halls also serve as meeting places. In November, at least 55 people were killed after a suicide bomber sneaked into a Kabul wedding hall where hundreds of Muslim religious scholars and clerics had gathered to mark the birthday of the Muslim Prophet Muhammad.
"Devastated by the news of a suicide attack inside a wedding hall in Kabul. A heinous crime against our people; how is it possible to train a human and ask him to go and blow himself (up) inside a wedding?!!" Sediq Seddiqi, spokesman for President Ashraf Ghani, said in a Twitter post.
The explosion shattered more than a week of calm in the Afghan capital. Ten days ago a Taliban car bomb aimed at Afghan security forces ripped through a busy west Kabul neighborhood in the same district, killing 14 people and wounding 145.
Saturday's blast occurred on the same road as the Aug. 7 explosion and came a few days after the end of the Muslim holiday of Eid al-Adha, with Kabul residents visiting family and friends, and just before Afghanistan marks its 100th independence day on Monday.
The blast comes at an uncertain time in Afghanistan as the United States and the Taliban attempt to work toward a deal to end a nearly 18-year war, America's longest conflict.
The Afghan government has been sidelined from those discussions, and presidential spokesman Seddiqi said earlier Saturday that his government was waiting to hear results of President Trump's meeting Friday with his national security team about the negotiations. Top issues include a U.S. troop withdrawal and Taliban guarantees not to let Afghanistan become a launching pad for global terror attacks.
While the Taliban earlier this year pledged to do more to protect civilians, it continues to stage deadly attacks against Afghan security forces and others in what is seen by many as an attempt to strengthen its position at the negotiating table.
The conflict continues to take a horrific toll on civilians. Last year more than 3,800, including more than 900 children, were killed in Afghanistan by the Taliban, U.S. and allied forces, the ISIS affiliate and other actors, the United Nations said.
The Associated Press contributed to this report.