The Monetary Authority of Singapore (MAS), is the central bank and financial regulatory authority of Singapore. It administers the various statutes pertaining to money, banking, insurance, securities and the financial sector in general, as well as currency issuance and manages the foreign-exchange reserves. It was established in 1971 to act as the banker to and as a financial agent of the Government of Singapore. The body is duly accountable to the Parliament of Singapore through the Minister-in-charge, who is also the Incumbent Chairman of the central bank.

The Monetary Authority of Singapore (MAS) was founded on 1 January 1971 with authority to regulate and supervise banking and finance in Singapore. It coexisted with the Board of Commissioners of Currency, Singapore established in 1967 to issue the city-state's currency, with which it eventually merged in 2002. Prior its establishment, its roles were performed by various government departments and agencies. The acronym MAS resembles mas, the word for 'gold' in Malay, Singapore's national language—although the acronym is pronounced with each of its initial letters.

During the COVID-19 pandemic, MAS brought forward its bi-annual meeting from some time in April to 30 March. The MAS decided to ease the Singapore dollar's appreciation rate to zero percent, as well as adjust the policy band downwards, the first such move since the 2008 financial crisis. This marks the first time the MAS had taken these two measures together.

Unlike many central banks around the world, the MAS is not independent from the Singapore Government—the MAS is under the purview of the Prime Minister's Office (PMO); chairmen of the MAS were either former or incumbent Minister for Finance. Some includes the former Prime Ministers or the current Deputy Prime Ministers.

Since 1981, monetary policy in Singapore is mainly conducted through the management of the exchange rate (rather than inflation targeting) of the Singapore dollar, in order to promote price stability as a basis for sustainable economic growth. The exchange rate is an intermediate target of monetary policy in the context of the small and open Singapore economy (where gross exports and imports of goods and services are more than 300 percent of GDP and almost 40 cents of every Singapore dollar spent domestically is on imports), the exchange rate represents a significantly stronger influence on inflation than the interest rate.

As a result, the nominal exchange rate, directly and indirectly, affects a wide range of prices in the Singapore economy, such as import and export prices, wages and rentals, consumer prices and output prices.

MAS operates a managed float regime for the Singapore dollar. The trade-weighted exchange rate, which is known as the 'Singapore dollar Nominal Effective Exchange Rate' (S$NEER) is allowed to fluctuate within a policy band; the level and direction of which is announced semi-annually (typically every six months) to the market. The policy band provides a mechanism to accommodate short-term fluctuations in the foreign exchange markets and allows flexibility in managing the exchange rate.

The exchange rate policy band is periodically reviewed by MAS to ensure that the policy band remains consistent with underlying fundamentals of the economy; the path of the exchange rate is continually assessed every 6 months in order to prevent a misalignment in the currency value. A Monetary Policy Statement (MPS) is released by MAS after each review, which provides information on the recent movements of the exchange rate and explaining the forward guidance of future exchange rate policy.

MAS would also release an accompanying report, the Macroeconomic Review (MR), which provides detailed information on the assessment of macroeconomic developments and trends in the Singapore economy; the MR is aimed to enhance market and public understanding of the monetary policy stance.

Singapore's debts are under the responsibility of MAS. As of 2022, the Singapore Government debt exceeds the country's GDP at about 150%. However, these are not net debts, but gross external debts, which can be traced to the debt liabilities in Singapore's banking sector—a reflection of the country's stature as a major global financial hub. In essence, Singapore borrows to invest, not to spend. Therefore, unlike other countries, Singapore is a net creditor with no debt to anyone, and has a net debt-to-GDP ratio of 0%, maintained for almost three decades since 1995.

Accordingly, Singapore is the only country in Asia with a AAA sovereign credit rating from all major rating agencies. For multiple years, Singapore emerged as the top country in the world with the least-risky credit rating under the Euromoney Country Risk (ECR) rankings, being one of the safest investment destinations. The country was also ranked as the freest economy in the world on the Index of Economic Freedom rankings.

Following its merger with the Board of Commissioners of Currency on 1 October 2002, the MAS assumed the function of currency issuance.

MAS has the exclusive right to issue banknotes and coins in Singapore. Their dimensions, designs and denominations are determined by the Monetary Policy Committee with Government approval. The banknotes and coins issued have the status of legal tender within the country for all transactions, both public and private, without limitation.

In December 2020, MAS approved digital bank licenses for 4 tech giants, Grab–Singtel consortium, Ant Group, Sea Group, and Greenland Financial consortium. Grab-Singtel and Sea Group were awarded digital full banking licenses, while Ant Group and Greenland Financial were awarded digital wholesale banking licenses. In May 2021, the ability to transfer money between Singapore's PayNow and Thailand's PromptPay was announced.