Sonny Randle was selected in the 19th round (218th overall) of the 1958 NFL Draft as a "futures" pick from Virginia. During his final college year, he focused on improving his track speed before joining the Chicago team in 1959. As a rookie, his playing time was limited, but he dedicated the offseason to refining his route running, practicing against teammates Dick "Night Train" Lane and Jimmy Hill. This effort helped convert his raw vertical speed into a highly developed skill. When the franchise relocated to St. Louis in 1960, Randle became a key player, leading the Big Red's passing attack and gaining national recognition.

Randle had explosive long strides that often outpaced coverage. His precise head fakes and quick breaks made him nearly unstoppable on double moves. In the red zone, his tracking ability and body position made him a top goal-line threat of his time.

His breakout season in 1960 showcased exceptional scoring efficiency. Randle led the NFL with 15 receiving touchdowns, setting a franchise record for a single season, and also recorded 62 receptions for 893 yards. His outstanding performance earned him First-Team All-Pro honors and initiated a three-year streak of Pro Bowl appearances from 1960 to 1962.

In the 1962 season, he achieved a career-high in yardage, with 63 receptions for 1,158 yards and 7 touchdowns, earning Second-Team All-Pro honors. The season’s highlight was a remarkable game at Yankee Stadium on November 4, 1962, when Randle set franchise records with 16 catches and 256 receiving yards against the New York Giants, records that remain unbroken.

Randle proved equally lethal in 1963, catching 51 passes for 1,014 yards and 12 touchdowns. After a shoulder injury shortened his 1964 campaign, he returned to peak form in 1965 with 845 receiving yards and 9 touchdowns, earning his fourth career Pro Bowl invitation.

Randle's 15 touchdown catches in 1960 remain the single-season Cardinals benchmark, and his 16 receptions for 256 yards against the Giants in 1962 stand as the team's untouched single-game records.  Randle departed for San Francisco in 1967, leaving St. Louis with an extraordinary legacy. Across eight seasons in a Cardinals uniform, he accumulated 328 receptions, 5,438 receiving yards, and 60 touchdown catches.