Retailers told the ONS that buyers may have purchased new outfits before lockdown restrictions were relaxed.
However, clothing sales remained well below pre-pandemic levels.
From Monday March 29, the government allowed outdoor meetings to resume in England, while groups of up to six people could drink or eat together in pubs and restaurants from April 12.
Other non-food stores reported a 13.4% increase, with medical suppliers suggesting older consumers were buying mobility equipment and venturing out more after being vaccinated.
Garden centers and florists also saw a 7.4% monthly growth, as those who stayed more at home during lockdowns spruced up their outdoor spaces.
Gas stations also saw strong growth of 11.1%, reflecting the easing of travel restrictions.
Samuel Tombs, UK chief economist at Pantheon Macroeconomics, said retailers benefited “immediately from the rebound in consumer confidence in March.”
He also pointed out that food stores may have taken advantage of the closure of restaurants, cafes and pubs during the reporting period, which lasted until one day before Easter Sunday.
Food retailers saw sales increase 2.5% in March, with specialty stores like butchers and bakers in particular registering strong trade, the ONS reported.
Elsewhere, online spending rose in March, up 0.6% from February 2021.
This is the industry’s strongest monthly growth since June 2020 and was largely driven by customers buying new clothes and shoes to refresh their wardrobes.
Lynda Petherick, Head of Retail, Accenture UK & Ireland, said: “After a year of what appears to be endless lockdowns, there is now a palpable sense of excitement among retailers and buyers alike.”
The proportion of online spending overall fell to 34.7% from 36.2% in February, but still remains well above the pre-lockdown figures.
But Ms Petherick added: “We expect online demand to remain strong after the reopening of non-essential retail.
“While retailers want to take advantage of the return of buyers to Main Street, they must also find a balance between their physical and digital offering, or risk losing to competitors who have learned strategic lessons from the pandemic.”
All non-essential stores in England and Wales were able to welcome customers from April 12, more than three months after they closed.
In the first week after the restrictions eased, figures from the British Retail Consortium indicated that footfall had jumped by almost 200% in England.
In Scotland, non-essential retail is set to reopen on April 26, while in Northern Ireland only the contactless click and collect system will be allowed for non-essential retail from April 12.