"This position comes with great responsibility, and I will commit every ounce of my energy to this football team, starting today," Patricia said in a statement. "My family is excited to become part of this wonderful city that displays so much passion for their teams.
"I can't express enough appreciation to the entire New England Patriots franchise, particularly Robert and Jonathan Kraft and their entire family. I will truly cherish these last 14 years as a member of this incredible organization."
The 43-year-old has been Bill Belichick's defensive coordinator in New England since 2012. In those six seasons, Patricia has never ranked outside the top 10 in scoring defense, winning two Super Bowl rings in that same time frame.
"On behalf of me and my family, I would like to congratulate and welcome Matt Patricia to the Detroit Lions as our new head coach," Lions owner and chairman Martha Firestone Ford said. "... I was most pleased with how we handled all the interviews and I am confident that we have found the right man to lead our football team."
"When we launched the search for our next head coach, I wanted to find a leader that could take us to the next level and I am confident we have found that in Matt Patricia," Lions general manager Bob Quinn added. "He has been preparing for this opportunity his entire career, and he's ready for the responsibility and its challenges."
Before his time as Pats DC, Patricia coached safeties, linebackers and offensive line (as an assistant OL coach in 2005) in New England. Patricia, who's been on the Pats' coaching staff since 2004, has never been a part of an NFL team that has won fewer than 10 games.