Miley, 29, was 11-11 with a 4.46 ERA in 32 starts in his first season with the Red Sox after four seasons in Arizona. He has a career 49-46 record with 3.95 ERA in 134 starts, and he was a 2012 National League All-Star and finished second in the NL Rookie of the Year Award balloting after going 16-11 with a 3.33 ERA.
"Wade is a proven Major League starter who brings a level of stability to the middle of our rotation," Dipoto said.
Miley has two years remaining on his contract at a combined $15.25 million, plus a $12 million team option for 2018 with a $500,000 buyout.