He was flown to the UK after being wounded when his vehicle was caught in a blast south of Kabul on Thursday.
He died of his wounds at the Queen Elizabeth Hospital, Birmingham, on Friday and next of kin were informed.
The number of UK personnel killed in Afghanistan since military operations there began in 2001 stands at 393.
Meanwhile, the head of the British Army - Gen Sir Peter Wall - has paid a pre-Christmas visit to UK forces in Afghanistan to thank them for their work.
He met servicemen and women at Camp Bastion in Helmand province.
Of the RAF serviceman, the MoD said it confirmed his death with "great sadness".
The explosion which caused his injuries is the same one that claimed the life of a Royal Marine on Thursday.
It has also emerged that a helicopter carrying UK troops made an emergency landing after coming under fire on Friday.
The Nato-led International Security Assistance Force (Isaf) said the forced landing, which occurred safely and without incident, took place in Nahr-e Saraj district, southern Helmand Province.
Isaf said the aircrew were recovered unharmed.
Earlier this week, Prime Minister David Cameron indicated he was planning a phased withdrawal of troops from Afghanistan.
Some 500 are due to be pulled out next year, with more expected to follow in 2013.
A Royal Air Force serviceman who was injured in an explosion in Afghanistan has died at a UK hospital, the Ministry of Defence (MoD) has said.