At a private party this summer at Little Prince, a French restaurant in SoHo, New Yorkers danced under disco lights and lined up at the bar.

And then there was Noah Syndergaard, a star pitcher for the Mets, who stood in a corner and spoke passionately — to anyone who would listen — about his book club.

“I got drafted out of high school in 2010, so I didn’t go to college,” he told one woman he had just met. “For me, reading is a way to continue my education,” continued Mr. Syndergaard, also known as Thor because of his long blond hair and 6-foot-6 build. “I want to have an exponential growth mind-set,” he said to another partygoer.

Mr. Syndergaard, who has been sidelined since 2019 because of an elbow injury, started his book club early this year with a tweet. “Hobbies include ice baths, being shirtless … and reading,” he wrote. “Now starting #NoahsBookClub. Dropping the first book on Feb. 1st. Let’s Read.”

He chose Scott Carney’s “What Doesn’t Kill Us” for the inaugural assignment. “This book is about becoming a stronger human being,” he wrote on Twitter. “I’ll check back in soon to hear your thoughts.” More inspirational nonfiction books have followed.

Anyone can join the book club by texting a phone number listed on Mr. Syndergaard’s social media profiles. Every month members get a message from him announcing the next book (although he makes the final call on selections, he takes suggestions, too).

Mr. Syndergaard posts photos of himself reading in different locations, from Sheep Meadow in Central Park to various dugouts across the city and country. He also interviews authors on Instagram live, asking participants to send in questions beforehand.

“I am getting better at this interview thing,” said Mr. Syndergaard, who expressed interest in possibly doing a podcast. “It makes me nervous a bit, and it’s out of my comfort zone, but I know it’s important and OK to be vulnerable,” he said of speaking with writers. According to Mr. Syndergaard’s agent, several thousand people have participated so far. It’s free for all users.

When Mr. Syndergaard found himself both injured and isolated at home during the pandemic, he had a lot of down time. He realized he was watching too much Netflix and Bravo (“Tiger King,” “Summer House”) and felt compelled to read more, he said. Starting the book club was also a way for him to stay connected to fans while benched.

At a time when celebrity competitors like Naomi Osaka and Simone Biles are encouraging fans to think of professional athletes as multidimensional human beings with feelings and problems and goals outside of sports, the book club has been a way for Mr. Syndergaard to tell the world he is more than simply a baseball player.

“I am not just a robot-athlete baseball player but a human being,” said the 29-year-old, who has managed to persuade many Mets fans to appreciate him for more than his right arm. Some are even reading more.

Ryan Hamilton, 41, who does shipping for Stumptown Coffee and lives in Ridgewood, Queens, goes to about six Mets games a year. “I’m so die-hard that sometimes I have to say to myself, ‘Why are you doing this? You are very heavily invested, and it’s causing you angst,’” he said, laughing.

He came across the book club on Mr. Syndergaard’s Instagram page and joined last month. “I have two kids, and I’m working, and I don’t get that much time to read, so I thought maybe if I sign up for this I will read more?” he said. “It has worked. I now allot time at the end of each night to read a chapter or two. It’s been very relaxing for me.”

Martha Esposito, a freelance writer who lives in Mount Laurel, N.J., appreciates the special connection Mr. Syndergaard generates with Mets fans. “These players get paid for what they do, and then can go home and do nothing else,” she said. “It’s nice that Noah is choosing to interact with his fans, who are actually the ones who pay his salary when you think about it.”

For the authors, being part of the club is a way to expand their audience. “Noah has real fans who are really engaged. They have real conversations, and there is real excitement,” said Mike Hayes, whose book “Never Enough” was the July selection.

“I don’t think I would have ever picked ‘Never Enough’ off the shelf without the suggestion from Noah Syndergaard,” said Greg Berry, 33, a math teacher in Long Beach, N.Y.

Some baseball purists have been critical of his effort to spread the joy of reading, questioning Mr. Syndergaard’s manliness or commitment to his sport in posts on social media.

Kate Fagan, who wrote “All the Colors Came Out,” the pick for June, was taken aback by the objections.

“There are these fans who want you to live, breathe, and eat the game,” Ms. Fagan said. “The thing I got to understand by being part of the book club is athletes are trying to fight preconceived notions just like the rest of us.”

Mr. Syndergaard, who intends to return to pitching before the season ends, possibly later this month, said he had been shocked by some of the negative commentary. “People are like, ‘Enough of this book nonsense, get back on the mound,’” he said. “First of all, I can multitask. I can only train with rehab so much of the day that it blows my mind.”

Mr. Syndergaard hopes that the book club will inspire more baseball lovers to broaden their interests, he said. “I just think that’s what being a New Yorker is all about, being hungry for more. That is exactly what I am doing. I am hungry for more knowledge and compassion and empathy,” he said. “That’s why I read.”