Pope Leo XIV blessed an autograph collector with his holy John Hancock … signing a baseball that’s now expected to bring in thousands of dollars at auction.

The head of the Catholic Church signed a ball for Randy L. Kaplan — a signature hawk who has spent the last few decades collecting signatures of world leaders and other prominent figures on baseballs.

Kaplan sent the Pope — a noted Chicago White Sox fan who actually attended Game 1 of the 2005 World Series — two White Sox caps … and, in return, Leo signed the ball.

The auction — administered by RR Auction — for the ball began Monday … and, it’s already generated a ton of interest with a dozen bids on the collectible in just a few days.

The total price currently sits at just over $3K … though it could go much higher — ’cause a ball signed by Pope Francis sold for $18,750 shortly after he passed away earlier this year.

BTW … Leo’s signature is in demand these days — ’cause a group of bikers rode a hog out to the Pope, and he signed it for a charity auction just a few weeks ago, right after he posed in the driver’s seat.