Do I need a transit visa at Istanbul Airport to enter Istanbul for city sightseeing? I am Malaysian citizen and I booked Turkish Airline flights to Malaysia (from Nice to Kuala Lumpur) with a 10-hour layover at Istanbul Airport.
No, you don't need a visa. Malaysian citizens are exempted from visa as stated by Turkish MFA.
Malaysia: Ordinary and official passport holders are exempted from visa for their travels up to 90 days.