The soldiers, the first of up to 70 set to be deployed there this year, are part of a United Nations (UN) peacekeeping mission to counter extremist group al Shabab.
The military personnel, from Force Troop Command, 1 Div and Field Army training, will offer medical, engineering and logistical support to the African Union Mission in Somalia (AMISOM).
The move reinforces the UK’s commitment to targeting terrorism around the world, said Defence Secretary Michael Fallon.
He added: ” This deployment is another demonstration of the flexibility and global reach of our Armed Forces.
“Alongside our efforts in Iraq, Syria and Nigeria, it shows our determination to tackle terrorism wherever it rears its head.”
Announcing the deployment in September as he prepared to attend a summit at the UN General Assembly in New York, David Cameron said “all the right force protection arrangements” would be put in place to minimise the risk of harm.
The Prime Minister also announced personnel would be deploying to South Sudan, where inter-tribal fighting has forced people from their homes and left millions facing a severe food shortage, to provide engineering work to strengthen infrastructure.
The assignments are part of the Strategic Defence and Security Review (SDSR) pledge to double the number of UK troops on UN peacekeeping tasks from the 300 currently deployed.