Mr Aden had moved to Beledweyne to boost the fight against insurgents
Five more people have died of their injuries after a suicide attack on the Somali security minister, bringing the total number of dead to 35.
Omar Hashi Aden was buried hours after the blast at a hotel in Beledweyne, north of the capital, Mogadishu.
The funerals for some of the other victims, who included Somali diplomats, are being held on Friday.
Mr Aden was an outspoken critic of al-Shabab, the militant Islamist group which said it carried out the attack.
The group is accused of having links to al-Qaeda.
The security minister had recently moved to Beledweyne, some 400km (249 miles) north of Mogadishu, in an effort to stop Islamist insurgents gaining more ground in Somalia, says BBC East Africa correspondent Will Ross.
The attack - by a suicide bomber who detonated an explosives-laden vehicle at the Medina Hotel on Thursday morning - has been widely condemned.
"This deplorable attack once again demonstrates that the extremists will stop at nothing in their desperate attempt to seize power from the legitimate government of Somalia by force," a statement from the African Union, European Union, United Nations and the League of Arab States and regional body Igad said.
"These extremists, both Somali and foreigners, failed in their recent attempted coup d'etat but are continuing their indiscriminate violence."
Mogadishu itself is calm after nearly 30 people died in a day of heavy fighting on Wednesday.
Both the government and insurgents deny targeting residential areas of the city.
Somali Prime Minister Omar Abdirashid Ali Sharmarke told the BBC's Focus on Africa programme the transitional federal government was still in control but urged the international community to help "before it is too late".
The failed Horn of Africa state has not had an effective national government since 1991 and some four million people - one-third of the population - need food aid, aid agencies say.
President Sheikh Sharif Sheikh Ahmed, a moderate Islamist, took office in January but even his introduction of Sharia law to the strongly Muslim country has not appeased the guerrillas.