During the investigation, the league also uncovered a separate violation made by the New York Yankees, and subsequently penalized the club "a lesser amount."
The sum of both fines will be donated to hurricane relief efforts, in the wake of Irma hitting Florida.
While Boston's fine stems directly from the sign-stealing fiasco between both clubs, the Yankees were penalized for an earlier violation involving the misuse of the dugout phone. However, MLB found insufficient evidence that the Yankees used YES Network cameras for the purposes of surveillance; an allegation made in the wake of the original Apple Watch probe.
"I'm glad it's over with," Red Sox president of baseball operations Dave Dombrowski told Michael Silverman of the Boston Herald. "I'm satisfied the (commissioner's) office did a thorough investigation," while adding that he's "sure this won't happen again."
"In assessing the significance of this violation, the investigation established three relevant points," MLB commissioner Rob Manfred's press release states, per Jared Diamond of The Wall Street Journal.
"First, the violation in question occurred without the knowledge of ownership or front office personnel.
"Second, when the Red Sox learned of the Yankees' complaint, they immediately halted the conduct in question and the cooperated completely in my investigation. I have received absolute assurances from the Red Sox that there will be no future violations of this type.
"Third, our investigation revealed that Clubs have employed various strategies to decode signs that do not violate our rules. The Red Sox' strategy violated our rules because of the use of an electronic device.
"Taking all of these factors as well as past precedent into account, I have decided to fine the Red Sox an undisclosed amount which in turn will be donated by my office to hurricane relief efforts in Florida."
Manfred set a more serious precedent going forward though, stating, "All 30 Clubs have been notified that future violations of this type will be subject to more serious sanctions, including the possible loss of draft picks."