[32] Karp was included in Publishers Weekly's 2022 list of 25 "book business change makers", or "seriously consequential individuals whose mark on the industry is indelible".

[33] In his role as chief executive, Karp testified in a 2022 antitrust trial filed by the Department of Justice to prevent Penguin Random House from acquiring Simon & Schuster.

While Simon & Schuster initially denounced the “online rumors,” intense pressure led the publishing house to send out an “acknowledgment” that the autograph had been rendered “in a penned replica form.” Buyers were then provided a refund.

[36] Karp is the longtime editor of John McCain; the two collaborated with Mark Salter on Faith of My Fathers (1999), Worth the Fighting For (2002), Why Courage Matters (2004), and The Restless Wave (2018).

According to The Wall Street Journal, some staff said the deal "would be a betrayal of the company's promises to oppose bigotry and make minority employees feel safe", but Karp insisted Simon & Schuster is "committed to publishing a broad range of views".

The Off-Broadway musical comedy, which is about a United Nations tour guide who realizes his ability to read minds after getting hit in the head by a melon, was first presented as I Know What You're Thinking in September 2000 at the New York International Fringe Festival and later ran at the arts complex New World Stages.

[9][20][41][42] In May 2011, Karp made a cameo appearance on the finale of Gossip Girl's fourth season ("The Wrong Goodbye"), in which he negotiates a manuscript deal with one of the show's main characters.