The industry lobby group the British Retail Consortium and KPMG said sales had risen 5.6% since April 2016 - up from a fall of 1% in March.
Food spending accounted for most of the growth, but shoppers were more cautious about other items.
The BRC said consumer spending would slow as inflation climbed.
Chief executive Helen Dickinson OBE said: "The positive distortion from the timing of Easter was largely responsible for the month's growth and looking to the longer-term signs of a slowdown, the outlook isn't as rosy."
According to the research, sales of food and drink soared over the long Easter weekend boosting total spending.
Over the three months to April, total food sales increased by 3.6% - much faster than the 12-month average of 2% growth, it found.
However, quarterly sales of non-food items grew more slowly at 0.7%.
Exceptions included sales of children's clothes and toys and furniture, although researchers said these rises were seasonal.
According to official statistics, UK retail sales posted their biggest quarterly fall in seven years in March, as the prices of everyday goods continued to climb.
The value of the pound has slumped by around 14% against the dollar since the EU referendum last June, pushing up the price of imported goods. This threatens to derail a consumer spending boom that has underpinned economic growth since the referendum.
Ms Dickinson said: "Although today's figures do indicate that consumers are still willing to spend, with a cocktail of rising costs and slowing wage growth as the backdrop, conditions for consumers will get tougher."
Retail sales jumped in April thanks to higher spending over Easter, although tougher times may be ahead, a survey has found.