The Patent and Market Court in Stockholm delivered its judgment on Wednesday, fining Google for 14.3 billion Swedish kronor plus interest (€1.7bn) as it found that Klarna's PriceRunner suffered harm due to the tech giant illegally promoting its own price-comparison tool in search results at the expense of rivals.
The court said PriceRunner was considered to have been damaged by Google's "unlawful favouring" of its own service over many years.
The award is one of the largest of its kind in Sweden.
In a statement to investors, Klarna welcomed the decision, though the figure falls well short of what PriceRunner had sought.
The company had claimed roughly 80 billion kronor (€7.2bn) meaning the court dismissed the majority of the claim while still siding with PriceRunner on the substance of the accusation.
