In September 2011, Miller attended the Boston Bruins' training camp, but was released to the Providence training camp on September 23, 2011.[2] After five games with Providence, Boston signed him to an entry-level contract,[3] opting to keep him with Providence for the 2011–12 season.
Miller attended Boston's training camp again in 2012, but was again later reassigned to Providence on September 14, 2012.[4] He spent the full 2012–13 season with the Providence Bruins, playing 64 games and scoring 16 points and competing in the Calder Cup playoffs for the first time.
Prior to the 2013–14 season, Miller was re-signed by the Boston Bruins to a one-year, two-way contract. However, to start the season, he was once again assigned to Providence, though he was later recalled to the NHL on November 20, 2013[5] and made his NHL debut in a game against the St. Louis Blues at TD Garden in Boston, becoming the first Bruins to wear the number 86.[6] Miller was then reassigned to Providence again on November 28, 2013,[7] but was recalled days later, on December 2, on an emergency basis.[8] He scored his first career NHL goal on December 8, 2013, against the Toronto Maple Leafs at the Air Canada Centre in Toronto. On January 21, 2014, Boston announced that they had re-signed Miller to a two-year, one-way contract extension.[9]
In October 2016 he signed a four-year contract extension at 2.5 million dollars a year.[10]
After missing the entire 2019–20 season due to a lower-body injury, and out of contract with the Bruins, Miller made it to the opening day of free agency before opting to re-sign with the Bruins on a one-year, $1.25 million contract on October 9, 2020.[11]
On July 14, 2021, Miller announced his retirement via Instagram.[12]