Another 182 civilians were wounded in the Saturday night explosion, government spokesman Feroz Bashari said. Interior Ministry spokesman Nusrat Rahimi confirmed the toll.
The Taliban have condemned the attack and denied any involvement in the blast that carried the hallmarks of an assault by the local affiliate of the Islamic State organization.
The blast occurred in a western Kabul neighborhood that many in the minority Shiite Muslim Hazara community call home, and the Islamic State affiliate has claimed responsibility for some attacks against the community in the past.
Rahimi said the attacker set off explosives among the wedding participants.
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, adding that 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."
Outside a local hospital, families wailed. Others were covered in blood.
The blast at the Dubai City wedding hall in western Kabul shattered a period of relative calm. On Aug. 7, a Taliban car bomb aimed at Afghan security forces detonated on the same road, killing 14 people and wounding 145 — most of them women, children and other civilians.
Kabul's huge, brightly lit wedding halls are centers of community life in a city weary of decades of war, with thousands of dollars spent on a single evening.
"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 wedding halls also serve as meeting places, and in November at least 55 people were killed when 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 Prophet Muhammad. The Taliban denied involvement in an attack that bore the hallmarks of the Islamic State affiliate.
Saturday night's explosion 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 under heavier security in a city long familiar with checkpoints and razor wire.
The blast comes at a greatly uncertain time in Afghanistan as the United States and the Taliban near 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 Donald 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.