"Donating these royalties to #OneFund! RT "@Nielsen_Ent: 'Sweet Caroline' sales up by 597 percent, selling 19K after Boston bombings," the 72-year-old singer-songwriter said on Twitter.
The soft-rock hit, released as a single June 28, 1969, has been played at Boston Red Sox baseball games as an eighth-inning staple since 2002 and became an unofficial Boston anthem after the April 15 bombings that killed three people and injured 264 others.
The nearly 19,000 downloads of "Sweet Caroline" this week is up from 2,800 the week before, Nielsen SoundScan reported.
The fund for the bombing victims, The One Fund Boston, raised nearly $24 million as of Thursday, a United Press International check indicated.
"Sweet Caroline," which doesn't mention Boston or the Red Sox, was inspired by an "innocent, wonderful" photo of President John F. Kennedy's daughter, Caroline Kennedy, Diamond told the British newspaper The Guardian in 2007.
Caroline Kennedy was 11 years old when he wrote the song. He sang it at her 50th birthday celebration in 2007.
Diamond was at Boston's Fenway Park Saturday to lead fans in a rousing sing-along rendition of the tune during the team's first home stand since the attacks.
The New York Yankees, Los Angeles Dodgers, Toronto Raptors and other sports teams also played "Sweet Caroline" at games following the bombings.
The singer, who has sold more than 125 million records worldwide, told Rolling Stone magazine last week he was working on a new song inspired in part by the Boston tragedy.
"I'm writing now and obviously affected by this situation in Boston, so I'm writing about it just to express myself," he said.
The song, which he told the magazine was still untitled, will cover more than just the Boston events. It will also include the shootings in Aurora, Colo., and Newtown, Conn.
"It's like an infestation, and I'm writing about the general situation, not just about this bombing in Boston, but what we're going through with all of these tragedies -- shootings and so on and so forth," Diamond said.