Davis was selected with pick number 181 in the 15th round of the 1956 NFL draft by the Cleveland Browns, but he did not start his career until the 1958 NFL season due to military service in the United States Army.[4] Davis wore number 77 and played at various positions on both offense and defense for the Browns, before being traded to the Green Bay Packers in 1960.[4]
Davis wore number 87 during his career with the Packers, where he was moved to a permanent position at defensive end by Vince Lombardi. For 10 seasons, Davis anchored the Packers' defensive line, playing 138 consecutive regular-season games and part of 162 regular-season games for his NFL career. Davis was a member of all five of Lombardi's NFL title-winning teams and played in Super Bowls I and II.
Davis played in an era when neither tackles nor sacks were official statistics. However, John Turney, a member of the Professional Football Researchers Association, reports that Davis had in excess of 100 sacks during his 10-year Green Bay career (1960–69), "possibly more than 120," including a minimum of 40 over the 1963–65 seasons alone.[5] Davis himself is quoted as saying, "I would think I would have to be the team's all-time leader in sacks. I played 10 years and I averaged in the 'teens' in sacks for those 10 years. I had 25 one season. [Paul] Hornung just reminded me of that the other day."[5] Davis earned All-Pro honors 5 times (1962, 64–67). He was voted to the Pro Bowl five times (1963–67).
Davis recovered 21 fumbles over his Packers career, which, more than three decades removed from his retirement, remains a team record. The Packers honored his retirement with a Willie Davis Day on December 21, 1969. Davis served on the team's Board of Directors.
During his early years with the Packers, Davis along with other players, lived in the Hotel Northland. He often told the story about how he along with the visiting officials, CBS broadcasters and crew, etc. were awoken on the morning of the Ice Bowl by a wake-up call from the front desk announcing the time and that the temperature was 17 degrees below zero.
Davis was also credited with following Vince Lombardi's lead in having no one associated with the team treat any man differently regardless of race. Davis would intentionally take the leadership position to offer to have lunch and dinner with players that had never played on an integrated team or eaten at the same table with an African American. Davis proactively and positively ensured that they acclimated well to Lombardi's culture of inclusion.
Davis' son is actor Duane Davis, known for his role as "Featherstone" in Necessary Roughness. He has a daughter, Lori Davis a lawyer known for her work in marijuana legislation within the Los Angeles children’s court system. Davis' grandson, Wyatt Davis, was an All-American guard at the Ohio State University, and currently plays for the New York Giants.[8] His granddaughter, Harley Ann Zepeda, is a beauty pageant queen who holds the title of Miss Los Angeles County United States.[9]
After being hospitalized for a month due to kidney failure, Davis died on April 15, 2020, at the age of 85.[10]
During the 2020 season, the Green Bay Packers wore a helmet decal to honor Davis, featuring his name and number.[11]
Previously named the Byron "Whizzer" White NFL Man of the Year Award, after Byron "Whizzer" White, the award was renamed in the fall of 2018 in honor of Alan Page.