One of two men on a motorbike opened fire at the man in his twenties late on Thursday outside his house in Huta, the capital of Lahij province, killing him on the spot.
Police said the attackers, presumed Islamist militants, escaped after the killing, the sixth such murder since the start of the year.
Similar killings in the impoverished Arabian Peninsula nation’s provinces of Abyan and Aden have been blamed on an Al-Qaeda-affiliated group, Ansar al-Sharia.
For the past year, Ansar al-Sharia has imposed Islamic law on areas of Abyan where it still holds sway.
Its so-called courts have tried and condemned to death several people accused of different crimes. Others have had hands amputated after being “convicted” of theft.
After an army offensive in May 2012 ousted the militants from areas they controlled, they holed up in mountainous regions of south and southeast Yemen.
From there they have launched regular attacks, mainly targeting the security forces.