As a rookie, Butler intercepted five passes for 142 yards. In 1953, he had nine interceptions and returned two of them for touchdowns. Four interceptions came in a game against the Washington Redskins on December 13, 1953. One of the interceptions resulted in a 35-yard return for a touchdown to win the game for the Steelers 14-13. The following year Butler set a record with two interception returns for touchdowns. In 1957, he led the league in interceptions with a career-best 10.
Offensively, Butler scored a touchdown against the New York Giants. It was late in the game and Butler had caught the game winning touchdown pass from Jim Finks.
In 1958, Butler added nine more interceptions to his growing list. During the 1959 season after garnering two interceptions, Butler was forced to retire due to a leg injury he received when tight end Pete Retzlaff of the Philadelphia Eagles rolled into Butler's knee.
Butler never made more than around $12,000 as a player with the Steelers. Following his playing career, Butler spent 46 years with the BLESTO Scouting Combine (44 as its director). During this time, his contributions to the NFL included scouting and evaluating over 75,000 college athletes and starting the Combine scouting process that is still in use today.
Butler was named to four straight Pro Bowls from 1956 to 1959. He had 52 interceptions during his career and 865 yards. At the time of his retirement, Jack ranked second in career interceptions, behind only Hall of Famer Emlen Tunnell.
In October 2008, Butler was named as one of the 33 Greatest Pittsburgh Steelers of all-time. The Steelers named players to this team as part of their 75th anniversary season celebration. He was named to the National Football League 1950s All-Decade Team. He was named as a senior nominee for the Pro Football Hall of Fame for 2012 and was elected as a member on February 4, 2012.