LONDON—British online car retailer Cazoo Holdings Ltd. said it would go public through a deal with a blank-check company that values the combined entity at $8.1 billion, as it capitalizes on a shift to online car buying during the pandemic.

Cazoo’s combination with AJAX I, a New York-listed special-purpose acquisition company led by U.S. billionaire investor Dan Och, comes less than two years after its online platform started selling used cars in December 2019. British serial entrepreneur Alex Chesterman founded the company in 2018. A private funding round valued Cazoo at $2.6 billion last September.

The coronavirus pandemic has helped upend the traditional model of visiting a showroom to buy a car as consumers have been forced to stay at home. In the U.S., auto makers have expanded their delivery programs, while dealers have upgraded their websites so customers can tour their showrooms virtually and carry out more of the buying process online.

While car sales overall have been depressed by the pandemic, sales of used vehicles in the U.S. have held up thanks in part to federal stimulus checks, lower interest rates and challenges getting new cars from manufacturers.

Online sales have done particularly well. Carvana Co. , a U.S. online seller of used vehicles, has seen its shares rise almost 400% since it went public in March 2020; its quarterly sales rose during the pandemic as dealerships remained closed.