In 1999, he was appointed Undersheriff of Bergen County. He subsequently became Sheriff from January 18, 2001 through January 1, 2002. In the days following September 11th, 2001, Sheriff Johnson served as commander of the force assisting the Port Authority Police securing the George Washington Bridge as part Bergen County's response to the terrorist attacks. When the newly elected Sheriff took office, Gordon Johnson was asked to continue with the Bergen County Sheriff's Department as Undersheriff and did so until 2005.

Senator Johnson retired with the rank of Major from the United States Army Reserve in 2000. He is highly decorated and holds the National Defense Service Medal, Bronze Star, Meritorious Service Medal, Southwest Asia Service Medal, NATO Service Medal, Kuwait Liberation Medal and many more. In 1990, Assemblyman Johnson served in Operation Desert Storm, where he was responsible for two Convoy Support Centers in the Saudi Arabian Desert. In 1996, he was deployed to Germany in support of Operation Joint Endeavor where he was part of a team that coordinated the activities and missions of the Civil Affairs units stationed in Bosnia.

Senator Johnson has a robust legislative track record that includes increasing access to education for New Jersey students, veterans, and DREAMer's. In 2015, Johnson was prime sponsor of legislation to enhance oversight of surplus military equipment being used by local law enforcement. Other legislative efforts include increased access to DNA testing to exonerate the wrongfully convicted. He has sponsored many bills to reduce gun violence, including limiting magazine size to 10 rounds and requiring gun stores to stock personalized handguns when they become available. As Chairman of the Commerce and Economic Development Committee, he was the prime sponsor of the Garden State Film and Digital Media Jobs Act which has brought the film and television industries back to New Jersey. Further legislative efforts include mandatory sexual assault training for police offices.

Gordon M. Johnson was raised in Englewood, New Jersey. He has served twenty-four years with the Englewood Police Department, attaining the rank of Patrol Sergeant. He is also experienced in labor relations and has served as President of the State P.B.A. Supervisory Officers Association-Local #216.

Senator Johnson graduated from St. Thomas Aquinas College in Sparkill, New York with a B.S. in Social Science and holds a Masters Degree in Administration and Supervision from Seton Hall University. In addition, he is a graduate of the United States Army Command and General Staff College in Fort Leavenworth, Kansas.

Senator Johnson was named Legislator of the Year by the ARC of New Jersey in 2016 and has been honored by the NJ Library Association, the Englewood Rotary Club, the NJ Small Business Development Center and many others.