Jared Remy was charged with first-degree murder after prosecutors said he fatally stabbed Jennifer Martel at the couple's apartment last August. Remy entered the plea at Middlesex Superior Court and was given a mandatory life sentence without the possibility of parole.
The elder Remy is a broadcaster at NESN in Boston and a former major league player with the Red Sox.
Jared Remy was arrested Aug. 13 after allegedly pushing Martel into a mirror. He was released from jail Aug. 14 and stabbed Martel to death the next day.
Remy and Martel have a 5-year-old daughter.
More from the Boston Globe:
Remy also faces charges involving a reported assault on a fellow inmate April 3 at the Cambridge jail where he is being held. He is to be arraigned next month on nine assault charges from that incident: six counts for allegedly striking the inmate with a plastic chair, one count each for allegedly using hot coffee and a bar of soap, and another for allegedly punching him.SI.COM STAFF: MLB Power Rankings: Blue Jays flourishing, Red Sox keep floundering