The tourist posted on her Xiaohongshu account on May 4: "This is Singapore. The [owner of the phone] is nowhere in sight, but their phone is still here."
She included the hashtag "the caliber of Singaporeans" in her post, paired with photos to describe what she claimed.
Her post quickly gained traction, with many netizens sharing similar views, Singapore news site 8days reported.
"I see a lot of people using their bags and wallets to chope seats as well," one user commented.
"Singapore has CCTVs everywhere; who would dare to steal?" said another netizen.
"Things generally don't get stolen here. You can leave a packet of tissue behind and still find it when you return," another commented.
Singapore, known for its strict laws and low crime rates, was named the safest country in Southeast Asia in a March report by Numbeo, the world's largest database of user-contributed data.
Under Singaporean law, those convicted of theft could face a prison sentence of up to three years, a fine, or both.