The owner of the Four Seasons in California’s Napa Valley is selling the recently opened hotel in one of the highest-valued lodging transactions ever, punctuating a year of blockbuster resort sales.

Sunstone Hotel Investors Inc., a real-estate investment trust, has agreed to pay about $175 million for the 85-room luxury hotel, according to people familiar with the matter. Real estate advisory firm and investment bank Eastdil Secured marketed the transaction for the seller, property fund manager Alcion Ventures.

The...

The owner of the Four Seasons in California’s Napa Valley is selling the recently opened hotel in one of the highest-valued lodging transactions ever, punctuating a year of blockbuster resort sales.

Sunstone Hotel Investors Inc., a real-estate investment trust, has agreed to pay about $175 million for the 85-room luxury hotel, according to people familiar with the matter. Real estate advisory firm and investment bank Eastdil Secured marketed the transaction for the seller, property fund manager Alcion Ventures.

The price tag amounts to about $2.1 million per hotel room key. When the Four Seasons sale closes, it will be the second highest valued U.S. hotel deal ever, according to data tracker CoStar Group.

Only Hyatt Hotels Corp.’s purchase earlier this year of the Ventana Big Sur resort in coastal California, which fetched $2.5 million a key, has been higher. Hotel owners like to measure sales on a price per key metric, which enables them to compare properties of different size and room count.

Sunstone in the spring agreed to acquire the Montage Healdsburg resort in California’s Sonoma County for $265 million, landing another high-price property in a sale that amounted to slightly more than $2 million a key.

This streak of big-ticket hotel transactions is a sign of how the luxury sector continues to outperform most of the industry during the pandemic. U.S. luxury average daily rates for the first nine months of this year were $336, compared with $303 for the same period in 2019, according to hotel data firm STR. Industrywide, STR said, average hotel room rates still lag behind their 2019 levels.

The top end of the market has performed especially well in places where resorts and other luxury properties are few and far between. The 2017 wildfires in California wine country damaged or destroyed some existing resorts in the area and the region has been a big draw the past year.

The new Napa Four Seasons is located at the base of Mount St. Helena. It is set within a working winery, surrounded by hundreds of acres of vineyards.

The resort opened on Oct. 1 and is already selling rooms at some of the highest rates in the country. A standard guest room for this coming Saturday night is available for $2,200, according to the Four Seasons website.

The Four Seasons Napa hotel sale is expected to close in the fourth quarter, say people familiar with the matter.

Write to Craig Karmin at craig.karmin@wsj.com