Pierre-Louis attended Boston College from 2010 to 2013, where he played for the Boston College Eagles football team. As a true freshman, he started all 13 games, finishing second on the team with 93 tackles. In 2011, he started the first nine games before missing the last three due to an injury. He still finished second on the team in tackles with 74, added seven tackles for loss, and returned a fumble 96 yards for a touchdown against UMass. In 2012, he started nine games for the Eagles, finishing the season ranked fourth on the team with 85 tackles, including four for loss, two sacks and three pass-break ups. As a senior, he started all 13 games, setting new career highs in tackles, tackles for loss and sacks. He also intercepted his first career pass, returning it 33 yards for a touchdown against Virginia Tech. After the season, he was named a first-team All-ACC.
Professional career
Seattle Seahawks
Pierre-Louis was drafted by the Seattle Seahawks in the fourth round of the 2014 NFL Draft. Pierre-Louis made his NFL debut on September 21, 2014 in an overtime win against the Denver Broncos, he recorded one tackle in the game. Pierre-Louis was placed on season-ending injured reserve for a shoulder injury. He finished the season with 10 tackles in seven games.
On March 17, 2018, Pierre-Louis signed a two-year contract with the New York Jets. On August 11, 2018, Pierre-Louis was suspended the first game of the 2018 season for violating the NFL's Policy and Program for Substances of Abuse. He played in nine games before being placed on injured reserve on December 29, 2018. On February 19, 2019, the Jets declined the option on Pierre-Louis' contract, making him a free agent at the start of the new league year.
Chicago Bears
On May 8, 2019, Pierre-Louis signed a one-year contract with the Chicago Bears. In week 16 against the Kansas City Chiefs, Pierre-Louis recorded a team high 12 tackles during the 26–3 loss. The following week against the Minnesota Vikings, Pierre-Louis recorded his first career interception off a pass thrown by Sean Mannion during a 21–19 win.
Pierre-Louis signed with the Washington Football Team on March 31, 2020, then known as the Redskins prior to a name change later that offseason.
Personal life
Pierre-Louis is of Haitian descent. His father is from Léogâne and his mother's family lives in Port-au-Prince. He has aunts and uncles who still live in Haiti, who operate sugarcane plantations, ice factories, and rent out property to the public.