The International Federation of the Red Cross and Red Crescent Societies said in a statement that the majority of the fatalities happened on the Yemeni island of Socotra, where 20 were killed.
The federation said in a statement Thursday another four were killed in Yemen's al-Mahrah governorate, which borders Oman, AP reported.
In Oman, authorities had previously said at least six people were killed by the storm.
Cyclone Mekunu made landfall on the Arabian Peninsula early May 26, causing flash floods and other damage. It earlier hit Socotra in the Arabian Sea.
The cyclone packed maximum sustained winds of 170-180 kilometers (105-111 miles) per hour with gusts of up to 200 kph (124 mph).