A study on e-commerce websites by Wolfgang Digital shows that Google generates 62% of all traffic and 63% of all revenue.
However, its influence is declining as consumers use different paths to buy on websites, with "dark traffic" on the rise.
This occurs when Google analytics does not recognise a source by default, like people sharing links on WhatsApp.
Analysing 143 million website sessions and €447m in online revenues, the study looked at key statistics for what drives traffic, clicks and purchases on a website. Participating websites included Littlewoods Ireland, Voya and McElhinneys.
The study showed that websites that got more mobile page views and more tablet page views grew revenue faster. 2017 is the first year mobile claimed more sessions (52%) than desktop (36%) and tablet (12%) combined.
But it also revealed that desktop generates 61% of all online revenue, with users 164% more likely to convert than those browsing on mobile. Desktop users also spent an average of 20% per order more than mobile shoppers.
Wolfgang Digital also said there was a strong inverse correlation between average page load time and revenue growth. Reducing the average load time by 1.6 seconds increased annual revenue growth by 10%.
Meanwhile, the number of clicks required to generate €1m online has grown by 12% in 12 months to over 360,000 clicks, up from over 323,000 in 2016.
Wolfgang Digital founder and CEO Alan Coleman said that Google is promising great advancements in analytics attribution later this year.
"It will be interesting to see if this increased visibility extends to cross-device conversions and social's role in conversion," he added.