An Ethiopian Airlines plane en route from Addis Ababa to Nairobi crashed six minutes after take-off on Sunday, killing all 157 people on board.
The incident followed Lion Air 737 Max 8 crash in October that killed 189.
Some in the aviation community have called for the aircraft to be grounded pending a full investigation.
But late on Monday, the Federal Aviation Administration (FAA) issued a “continued airworthiness notification” saying the plane was safe to fly.
China, Indonesia, and Ethiopia on Monday ordered their airlines to ground the jet. Aerolineas of Argentina, Mexico’s Aeromexico and Brazil’s Gol have also suspended flights of the aircraft.
The Civil Aviation Authority of Singapore on Tuesday said it was “temporarily suspending the operation of all variants of the Boeing 737 Max aircraft into and out of Singapore”.
The suspension will take effect from 14:00 local time (06:00 GMT).
Other airlines kept flying the 737 Max 8 after Boeing said it was safe.