In the country's deadliest single attack since 2011, the bomber detonated his explosives among packed crowds watching a tournament featuring three local teams in the volatile province of Paktika.
The bloody attack underlined the challenges facing President Ashraf Ghani, who came to power in September, as US-led NATO troops wind down operations and Afghan security forces take over responsibility.
Ghani was among those who visited victims being treated for wounds at a 400-bed military hospital in the Afghan capital.
"Last night 54 people wounded by the terrorist action in Paktika were transferred by military helicopter to the Sardar Mohammad Daud Khan hospital (in Kabul)," Zahir Azimi, spokesman for the defence ministry, said via Twitter.
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There was no immediate response from the Taliban, but the insurgents often distance themselves from attacks that claim mostly civilian lives.
The blast, in the Yahya Khail district of Paktika, came at about 1230 GMT as hundreds of people had gathered to watch the volleyball, a popular sport among young men in Afghanistan.
Paktika, one of the most restive provinces in Afghanistan, borders Pakistan's lawless tribal areas, where many insurgent leaders seek safety from NATO and Afghan forces.