According to data from AdGooroo, a Kantar Media-owned company which tracks keywords, British retailers spent 24% more on search in the first half of 2016 compared to the same period last year.
Advertisers spent £26.7m, up from £21.6m the prior year.
Amazon spent its cash on 216 keywords with an average clickthrough rate of 2.8%.
It was followed by Apple, which spent £508,000 on 28 keywords, with an average clickthrough rate of 4.3%.
John Lewis spent £505,000 on 141 keywords, with an average clickthrough rate of 3%.
Mobile retailers dominated the top 10, spending a total of £2.2m.
O2, Carphone Warehouse and Argos rounded out the top five spenders, while the rest of the top 10 featured brands such as EE, Three and Samsung.
AdGooroo measured spend on Google text ads on desktop for the top 250 retail keywords, across categories such as mobile phones, apparel and accessories, home improvement and shoes.
The most popular keywords by paid search spend were 'iPhone 6s', 'engagement rings', 'Samsung Galaxy S6' and, surprisingly, 'business cards'.
The top ten brands by paid search spend
John Lewis: £505,000
Carphone Warehouse: £474,000