Sales from the song are up by 597 percent, Nielsen SoundScan said Wednesday. The singer's representative said Diamond will donate the recent sales to marathon bombing victims.
"Sweet Caroline" sold 19,000 tracks this week. It sold 2,800 tracks the previous week and 1.75 million tracks to date.
The tune is a staple of Boston Red Sox games. It makes no specific mention of Boston or the Red Sox, but the team started playing it regularly at Fenway Park more than a decade ago and fans took to it.
The New York Yankees, Toronto Raptors and other professional sports teams also have played the song at games in the days after the deadly blasts April 15.
Diamond released "Sweet Caroline" in 1969. The song was inspired by Caroline Kennedy's name.
The Associated Press contributed to this report.