Waitrose was the biggest winner, attracting 11% more shoppers and sales growth of 19.5% over the month.
Sales were driven by a 24% year-on-year increase in advertising by the 10 supermarkets tracked by information and insights company Nielsen, totalling £32.9 million in the four weeks to March 30, reflecting that Easter did not fall within the four weeks ending March 31 last year as it did this year.
The seasonal increase in sales was driven by confectionery, up 41% year-on-year, beers, wines and spirits (up 12%), bakery (up 10%) and packaged groceries (up 8%).
Nielsen's UK head of retailer insight, Mike Watkins, said: "Although 'spend on offer' moved up slightly to 34% of sales with business as usual in-store promotions, the early Easter was the key factor in the March sales uplift supported by a robust increase in advertising spend.
"Although all the grocery multiples benefited, Waitrose was able to surf the rising Easter tide better and longer than its competition."
Waitrose was responsible for the biggest year-on-year increase in spending, up 142% to £2.5 million, followed by Sainsbury's, up 82% to £2.7 million.
Asda was the only one of the top five supermarkets to reduce its advertising spending, down 19% on the same period last year.
Mr Watkins said: "Waitrose's significant increase in TV and press spend helped attract 11% more shoppers and contributed to stellar sales growths of 19.5% in the last four weeks."