Brownlow attended Cathedral High School, winning the Indiana 3A state high school championship in 1986. He accepted a football scholarship from the University of Illinois. In his first year he was named captain of the special teams units, becoming the first freshman in school history to be named a game captain. As a sophomore, he was named the starter at middle linebacker, led the Big Ten Conference in tackles with 155 and became the leader of the Illini defense. The next year he posted 130 tackles. As a senior, despite mid-season back and ankle injuries, he finished with 155 tackles, one interception and one fumble recovery. He became only the fifth player in school history to receive All-Big Ten honors in three consecutive seasons. He was named the Big Ten Conference Defensive Player of the Year and placed second in the balloting for the Butkus award. He also received the 1991 Hula Bowl defensive MVP award, after making 9 tackles, one interception and one fumble recovery. He was named by the media to the Illini 1980s All-Decade Team and ranks third on the Illinois' career tackles list.
Brownlow was selected by the Dallas Cowboys in the fifth round of the 1991 NFL Draft, after dropping because concerns with his size. As a rookie, he had an impact playing on the special teams units, which included blocking a punt that helped upset the Chicago Bears in the Wild Card Playoff win.
On September 1, 1992, he was claimed off waivers by the Tampa Bay Buccaneers. He started the last four games of the 1992 season. Although he was cut on September first, 1993, he was later re-signed during the second week of the season, posting 9 defensive tackles and 11 special teams tackles.
Brownlow signed with the Dallas Cowboys in 1994 to help upgrade the coverage units and led the team in special teams tackles with 27.
Washington Redskins
On March 16, 1995, he signed as a free agent with the Washington Redskins. He received recognition as one of the best special teams players in the league at different times during his six-year career and retired in 1997 after never missing a game.
Personal life
Brownlow currently resides in Indianapolis with his wife and three kids. Upon retiring from the NFL, he earned an MBA from Indiana Wesleyan University and is the owner of several businesses in Indianapolis. He is also an assistant football coach at his alma-mater, Cathedral High School.
