The troops, who conducted counterterrorism operations against al-Qaeda and its affiliated groups, were leaving the al-Anad airbase in Lahj province on Saturday citing security concerns
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The personnel, who worked in coordination with the Yemeni government in controlling drone operations, were the last US forces stationed in the country.
Al Jazeera contacted the US military for further comment but officials have so far declined to comment.
The evacuation comes a day after suicide bombers, reportedly pledging allegiance to the Islamic State of Iraq and the Levant (ISIL), killed at least 137 worshippers and wounded hundreds more at two mosques in the capital Sanaa.
Washington, which considers Al-Qaeda in the Arabian Peninsula (AQAP) one of the most dangerous wings of al-Qaeda, had lent financial and logistical support to Yemen's government in combatting the armed group.
President Abd-Rabbu Mansour Hadi, who has since fled the capital to the southern port city of Aden, has been a vocal supporter of the US war against al-Qaeda, at one point saying he approved each US drone strike