Drafted in the seventh round (163rd overall) of the 1970 NFL Draft out of Lincoln University of Missouri, Lemar Parrish stepped onto the professional scene as an unheralded small-school prospect. It took almost no time for "Leapin' Lemar" to establish himself as one of the most explosive, multifaceted defensive backs and return specialists in the game.

Parrish blended flawless, mirror-like coverage abilities with exceptional speed in open field situations. Playing as a left cornerback, he demonstrated smooth hip movements to turn and track elite receivers, keen instincts for intercepting passes, and superior vision when handling the ball. Each time he intercepted a pass, returned a punt, or recovered a loose ball, Parrish was a constant threat to score a touchdown.

Parrish's rookie year in 1970 was remarkable, as he started 11 games at cornerback, making five interceptions, scoring on a 95-yard kickoff return, and returning a blocked field goal 83 yards for a touchdown. His all-around performance quickly earned him a Pro Bowl selection. In 1971, he continued to excel with seven interceptions and another touchdown, earning his second consecutive Pro Bowl.

Although he had excellent defensive performances in 1972 and 1973, with five interceptions and three non-offensive touchdowns in those two seasons, he was surprisingly not selected for the Pro Bowl.

Parrish responded by achieving an impressive four-year streak of accolades from 1974 to 1977. In 1974, he earned Second-Team All-Pro honors and a Pro Bowl selection after leading the NFL with a remarkable 18.8-yard punt return average, returning two punts for touchdowns. He continued his success with another Second-Team All-Pro and Pro Bowl appearance in 1975, secured a third straight Pro Bowl invite and earned First-Team All-Pro honors in 1976, and concluded his Bengals career with a fourth consecutive Pro Bowl in 1977.

After the 1977 season, contract disagreements resulted in Parrish being traded to the Washington Redskins. He maintained his high level of performance in the capital, intercepting 21 passes over four seasons, earning two further Pro Bowl selections (1979, 1980), and receiving a First-Team All-Pro honor in 1979.

In Cincinnati, Parrish played 105 games (101 starts), with 25 interceptions (fifth in franchise history) and 13 non-offensive touchdowns from interceptions, punts, kickoffs, fumbles, and blocked kicks—a franchise record. In 2024, he was inducted into the Bengals Ring of Honor, cementing his legacy.