'Senior Chief Kyle Milliken embodied the warrior spirit and toughness infused in our very best Navy SEALs,' Rear Admiral Timothy Szymanski, Commander, Naval Special Warfare Command said in a statement.
'We grieve his death, but we celebrate his life and many accomplishments. He is irreplaceable as a husband, father, son, friend and teammate - and our thoughts and prayers go out to his family and teammates.
'His sacrifice is a stark reminder that Naval Special Operators are forward doing their job, confronting terrorism overseas to prevent evil from reaching our shores.'
A Department of Defense official said Milliken was killed near Barii, about 40 miles west of the Somalian capital, Mogadishu.
'The service member was struck by small arms fire while conducting an advise and assist mission alongside members of the Somalia National Army,' Mack said.
The other injured service members are receiving proper medical attention and were taken to neighboring Djibouti for care.
Both the United States and Somalia in recent weeks have declared new efforts against al-Shabaab.
US forces in helicopters raided an al-Shabaab hideout near the Somali capital on Thursday night and engaged with fighters, according to a Somali intelligence official who confirmed the US military operation.
The official, who spoke on condition of anonymity because he was not authorized to speak to the media, said the helicopters dropped soldiers near Dare Salaam village in an attempt to capture or kill extremists in the area.