Indonesia came in second with tourist spending at S$2.2 billion, followed by Australia (S$1.5 billion), The Strait Times reported citing a report from the Singapore Tourism Board.
The report also revealed the island city state's tourism receipts last year reached around an estimated S$25 billion, surpassing an earlier forecast of S$21 billion.
The average length of stay also rose to 3.8 days in 2023, higher than 3.4 in 2019.
Last year, Singapore received 13.6 million foreign arrivals.
The top source markets were Indonesia (2.3 million), China (1.4 million) and Malaysia (1.1 million).
Singapore and China have agreed to a 30-day mutual visa-free entry for their citizens, which will formally come into force on Feb. 9 - the eve of the Lunar New Year.