The team issued a statement indicating Valentine would be announced as the new manager at a Thursday press conference. The former New York Mets and Texas Rangers manager will be undertaking his first managerial assignment in nearly 10 years.
Valentine managed the Texas Rangers from 1985-92 and then managed the Mets for six-plus seasons beginning in 1996 before being fired in 2002. He compiled a major league regular-season record of 1,117-1,072.
His hiring is the first major decision by Red Sox General Manager Ben Cherington, who took over the club after Theo Epstein left to run the baseball operations for the Chicago Cubs.
Former Manager Terry Francona left the Red Sox in September after winning two World Series titles in eight seasons. His departure was hastened by a late collapse that cost Boston a playoff berth.