Flight AF 463, which had 459 passengers and 14 crew members on board, had left Mauritius at 9pm local time (1700 GMT) and was due to arrive in Paris Charles de Gaulle at 5:50am (0450 GMT).
It landed at Moi International Airport, Mombasa, before 1am local time (2137 GMT).
“It requested an emergency landing after a device suspected to be a bomb was discovered in the lavatory, an emergency was prepared and it landed safely and all passengers evacuated,” police spokesman Charles Owino said.
“Bomb experts from the Navy and the CID were called in and took the device which they are dismantling to establish if it had any explosives,” he said.
The plane was still in Mombasa airport in the early morning, he added.