42-year-old Captain Mark Hale was fatally wounded in Helmand province after he was caught in an explosion while attempting to rescue another soldier.
Captain Hale was based at the Ballykinlar British Army Camp in Co Down and lived nearby in Dromara.
He was buried with full military honours following a service in Hillsborough Parish Church.
Separately, the UN has condemned a suicide attack that killed Afghanistan's deputy head of intelligence and several other government officials as 'indefensible'.
A suicide bomber killed at least 23 people in the attack near a mosque in eastern Afghanistan.
Abdullah Laghmani of the National Directorate of Security was one of the highest-ranking security officials in President Hamid Karzai's government to be killed.
The attack was also one of the biggest this year.
The bomber struck near a mosque in the provincial capital Mehtar Lam in mountains about 100km east of Kabul.
