Following a slump in prices and spending across the board, inflation fell to 0.5 per cent in May, down from 1.3 per cent in April.
The Bank of England's "baseline" or target for inflation is two per cent, which is a stable level that promotes healthy economic growth.
The Consumer Prices Index - which shows how much spenders' money is worth in relation to goods and services - is the most widely-used measure of inflation in the country.
Its decline of a staggering 0.8 per cent in just a single month came as fuel prices dropped more than 16 per cent, and clothing and footwear prices fell by over three per cent amid "heavy discounting".
According to ONS deputy national statistician Jonathan Athow, this was the "lowest annual rate in four years".
"The cost of games and toys fell back from last month's rises, while there was a continued drop in prices at the pump in May, following the huge crude price falls seen in recent months.
"Outside these areas, we are seeing few significant changes to the prices in the shops."
The only sector contributing to an increase in inflation, according to the ONS, was food and alcoholic beverages, which saw a price rise of around 0.05 per cent.
All other sectors the ONS influenced the CPI negatively or maintained an overall neutral balance, with the transport (including oil and gas) and leisure industries bringing inflation down by almost 0.1 per cent each.
On a broader chart, however, it looks to be good news for the UK's workforce, as wage growth continues to be higher than inflation - although only just, at 1.7 per cent.
The three months to January, however, saw the same figure sitting around four per cent - meaning that wage growth has seen a similar, expected fall in recent weeks.
Inflation also has a significant impact on the Bank of England's borrowing base rate, which currently sits at 0.1 per cent after a rapid response from its Monetary Policy Committee deciding to drop it from 0.25 per cent.
This is the lowest the base rate has been for over 300 years, and with inflation figures in freefall, it looks as if this will continue to be the case for quite some time.
