Bloom agreed to a contract on Friday but the official announcement will not take place until at least Monday, the Boston Globe reported.
Bloom, 36, comes to the Red Sox from the Tampa Bay Rays.
The Red Sox finished the season with a record of 84-78 and missed the postseason for the first time since 2015.
Bloom, a native of Philadelphia, graduated from Yale University in 2004 and was an intern with Major League Baseball, and then the San Diego Padres before joining the Rays, where he has worked for the last 15 years.
He was named Tampa Bay’s senior vice president of baseball operations in 2016. The Mets reportedly considered Bloom for their General Manager position last fall.
Bloom frequently has to explain that his name is pronounced High-em, telling Tablet Magazine in an interview in April that he has given up on people pronouncing the guttural “ch” sound.
Tablet reported that Bloom, his wife and two sons live close to the Rays Tropicana Field so that Bloom, who is Sabbath observant, can walk to home games on Friday night.
He attended Solomon Schechter and Akiba Academy Jewish day schools while growing up in Philadelphia.