IMRG Capgemini e-Retail Sales Index also recorded a 13% rise YoY.
Online sales grew 13 percent year-on-year in April, according to the the IMRG Capgemini e-Retail Sales Index.
The Index, which tracks online sales in the UK, also found that sales rose 4 percent in April compared to March. This was the latest phase in four months of single digit growth.
April also saw 2015’s highest conversion rate at 4.6 percent. Particularly strong increases were seen in clothing, where sales growth rose 15 percent, and travel, where sales were up 20 percent.
A key driving factor was mobile, with the research revealing that mobile sales grew 52 percent year-on-year and eight percent in March.
Since the Index was established in April 2000, online sales have risen 11,000 percent and around £640 billion has been spent online.
Alex Smith-Bingham, Head of Digital, Consumer Products and Retail, Capgemini, commented: "Today’s figures show a return to form for online retail. Shoppers are clearly more confident than ever and in the run up to the general election were feeling upbeat about their prospects for the future.
"The fact that conversion rates were so high goes to show that people weren’t just window shopping – they were going online ready to spend. With the economy continuing to improve I’m confident that online retail is on the up."
Tina Spooner, Chief Information Officer, at IMRG said: "The return to double-digit growth during April has resulted in overall growth of 9% year-to-date for the UK online retail market. Although this is still below our 2015 growth forecast of 12%, a number of sectors continue to outperform the total market including footwear, lingerie and accessories.
Spooner added: "The latest results also reveal that online browsers converted at the highest rate for April since 2009 – helping to fuel the 3.9% month-on-month rise between March and April, where the established trend is for flat growth.
"A separate survey of IMRG members has revealed that UK retailers believe a number of factors influenced the slowdown in e-retail growth during Q1 including market maturity, increased competition, less discounting resulting in consumers holding out for sales and promotions and also political and economic uncertainty.
"However, it is too early to say whether the single-digit growth recorded during Q1 was merely a blip and we will be monitoring developments very closely over the coming months."