After retiring from the NFL, Mayhew attended Georgetown University Law Center. He graduated in 2000 with a J.D. degree. Mayhew joined the Lions front office in 2001 and was appointed senior vice president and assistant general manager in 2004 by Matt Millen and served as assistant to Matt Millen through 2008. Mayhew was promoted to acting General Manager of the Detroit Lions after the firing of Matt Millen. On December 29, 2008 it was announced that Mayhew would be officially promoted to General Manager. Mayhew's first move as acting General Manager was the trade of wide receiver Roy Williams and a 7th round draft choice to the Dallas Cowboys for Dallas' 1st, 3rd and 6th round draft choices in the 2009 NFL Draft. Throughout his professional career, Mayhew has contributed to several community endeavors both as a player and as an executive. In 1993, while playing for Tampa Bay, Mayhew was given the Chelo Huerta Community Service Award, and the following year he was a nominee for the True Value HardwareMan of the Year. From 1995-96, Mayhew was the Bucs’ United Way Spokesperson. Mayhew is a member of the Florida Bar. Additionally, Mayhew is a member of the Board of Trustees for the Henry Ford Museum and Greenfield Village and Board of Directors of Detroit PAL. For the past six years, he has hosted the Martin Mayhew Youth Football Coaching Academy for approximately 100 coaches from Detroit PAL. The purpose of the camp is to provide additional teaching and training tools for coaches so they can continue having a positive and long-lasting impact on the young lives they touch through youth football. On November 5, 2015, Mayhew was fired by the Detroit Lions on the heels of a 1–7 record at the time of their bye week. During his tenure as general manager, the Lions were 41–63 and made the playoffs twice, losing both times in the Wild Card round. He was hired by the New York Giants in 2016. He is the father of Sierra Mayhew, founder of styleintheway.com and college student at the University of Notre Dame, Ryan Mayhew, college student at the Pennsylvania State University, and Justin Mayhew, a student at DCDS.
