The childhood home of the first American pope will be sold to the highest bidder in an online auction in June, a new marketing strategy for a three-bedroom house that was originally listed for $199,000.

The current owner of the humble house in Dolton, Ill., switched gears last week when he realized he had hit a real estate jackpot. As Pope Leo XIV was introduced to the world, the owner learned that the new pontiff, who grew up as Robert Francis Prevost, spent at least some of his childhood in the brick Cape Cod-style house on 141st Place, about 30 minutes south of downtown Chicago.

Offers began pouring in almost immediately, said Steve Budzik, the real estate broker for the property. He had fielded only a handful of offers in recent months. Mr. Budzik and the owner, Paweł Radzik, 36, quickly pulled the house off the market as the two figured out what to do next.

Mr. Budzik said it felt impossible to set a price for the home now that they knew its unique history. So they turned to Paramount Realty, a real estate auction firm that had held an auction in 2017 for another unassuming house: a five-bedroom Tudor in Queens where Donald Trump lived until age 4. It sold for $2.14 million, more than double the average of comparable houses in the area.

Paramount has begun collecting bids for the property in Dolton on behalf of Mr. Radzik, who purchased the home a year ago with a plan to renovate and flip it. The online auction will be held on June 18.