The strike took place on Friday in the vicinity of Harardhere, about 480km north-east of Mogadishu, Somalia's capital, the military said in a statement on Tuesday.
The airstrike was launched in coordination with the Somalian government Friday near the Harardere community in Mudug province in central Somalia.
The US said the attack was carried out as part of a joint effort with Somali forces to hit the al-Shabab group.
USA military officials have expressed concern that the group is again growing - even after losing much of its territory in Somalia in recent years and being targeted by United States drone strikes.
A year ago there were 31 such attacks and 15 in 2016, according to the Foundation for Defence of Democracies, a Washington-based research institute.
The report also indicated air assaults and missile strikes had increased in recent months against al-Shabaab.
But the camp's location far north of the extremist group's usual strongholds indicates its reach, analysts said.
AFRICOM said that they are committed to preventing al-Shabaab from taking advantage of safe havens from which they can build capacity and attack the people of Somalia.
In 2017, the military carried out 35 airstrikes in Somalia - 31 against al-Shabab fighters and four against Islamic State militants, according to Roggio.
Some of the al-Shabaab fighters killed in the U.S. airstrike, who had gone through months of training, were being prepared to carry out suicide bombings on Somali and AU bases while others were foot soldiers meant for complex attacks across central and southern Somalia, one of the Somali intelligence officials said.
It is noted that the Armed forces of the United States held this year, more than two dozen air strikes against "al-Qaeda" associated with "Al-shababa", the most deadly Islamic extremist group in the countries of Africa South of the Sahara.
The US says it continues to support that transfer even as some US military officials have joined AU officials and others in expressing concern that Somalia's forces are not yet ready.