The targeted man was the logistic officer of the integrated security forces of Galkayo.
Another security official was wounded in the bomb attack. No group has yet claimed responsibility for the car bombing reported in the divided town.
In the past, Al-Shabaab carried out killings and attacks in the city, which has been the scene of clashes between Galmudug and Puntland forces.
Meawhile, United Nations (UN) representative in Mogadishu has held talks with the leadership of Upper House on the country's electoral law which was recently approved by the Lower House.
Late last month, Lower House approved the election law which is a significant step towards universal suffrage elections 2020.
During the voting 171 lawmakers voted in favor of the legislation, 5 rejected and 2 abstained.
During a meeting, UN envoy, James Swan, and Somali Upper House speaker, Abdi Hashi Abdullahi have discussed the bill.
"UN envoy James Swan today met with the Speaker of the Upper House, Abdi Hashi Abdullahi, and discussed the country's draft electoral bill - he described it as historic legislation in Somalia's state-building process, and urged its timely adoption to enable the 2020 #elections," UNSOM said in a Twitter post.
The draft law will become a law if passed by the Senate (upper house) and signed by President Mohamed Abdullahi Farmajo.
Somalia last held one-person, one-vote elections in March 1969 when the government was overthrown in a bloodless military coup, according to the UN.