Lim Cheng Hoe, who spent 38 years in public service and received the Public Administration Medal (Silver) in 2009, was initially facing 60 counts of cheating of about S$89,000 ($70,691).
The remaining 50 charges will be taken into consideration during his sentencing hearing Thursday afternoon.
From 2008 to 2012, Lim is said to have cheated the ministry by submitting false expense claims for wine and pineapple tarts, which are popular in the foreign ministry as gifts for hosts of official trips abroad.
The claims he had allegedly submitted ranged from S$280 to $5,080.
Lim, who is now suspended from duty, was protocol chief for about 10 years. He headed the ministry's section responsible for organising ministerial and presidential trips overseas, and also oversaw the diplomatic protocol affairs.
The maximum penalty for cheating in Singapore is 10 year's jail and a fine.
The prosecution is urging for a sentence of 18 months. He will be sentenced Thursday.
Lim's case is the latest in a series of corruption cases involving senior government officials in Singapore, which has been known for having the cleanest government in Asia over the past several decades.
Singapore leaders have said that the system remains efficient in curbing corruption and that the public should continue to have faith in it.