Lynch had been chosen to play in the annual College All-Star game, causing him to miss the first two weeks of Chiefs ' practice. By the time Lynch made it to camp, Lanier had already established himself as the team's middle linebacker, and the American Football League had another first: the first black middle linebacker in Professional Football history. In the midst of a solid first season, Lanier suffered an injury and missed the last four games of the year
The following year, Lanier collected four interceptions, then matched that total in 1969 as he helped the Chiefs capture Super Bowl IV with a 23-7 upset of the Minnesota Vikings. Lanier was stellar in the Super Bowl, recording 7 tackles and an interception. Lanier later commented on the increased motivation that Chiefs players felt because of wearing an AFL patch to honor the league's final year.
There were numerous great moments throughout his career, but none exemplifies his heart and desire as much as the Chiefs' goal line stand against the New York Jets in the 1969 divisional playoff game. Leading 6-3 in the fourth quarter, New York had a first-and-goal at the Chiefs' one-yard line after a pass interference call on Kansas City. It was then that Lanier made an emotional appeal to the rest of the Chiefs defense. "They're not going to score!" Lanier yelled at this teammates. "They're not going to score!" The Chiefs shut down the Jets on three straight plays and held them to a field goal. When Kansas City scored a touchdown on its next possession, the game was over. The first important step to the Super Bowl was complete.
In 1972, the Chiefs moved to Arrowhead Stadium, but the change would not serve the team well, since by 1974, the team's talent had been depleted by age and injuries. After the conclusion of that season, Stram was fired after 15 years at the helm.
The linebacking trio of Lanier, Lynch and fellow Hall of Famer Bobby Bell is recognized as one of the most talented in professional football history, lasting until the arrival of new head coach Paul Wiggin in 1975.
Lanier was known as Contact, a name coined by Chiefs' teammate Jerry Mays in 1967. As Lanier remembered: "Since I unfortunately followed the style of tackling that we were taught at that time - that was to use your head first of hitting players in the middle of their body. It was done in a rather aggressive manner".
But Lanier's uncontrolled tackling resulted in Chiefs' equipment manager Bobby Yarborough outfitting Lanier's helmet with extra padding. The padding was not on the inside of the helmet to protect Lanier but rather, as some photos of him in uniform show, on the outside of the helmet to protect the player he was tackling.
While renowned for his hitting ability, Lanier was also fast, agile and disciplined, finishing his career with 27 interceptions and 15 fumble recoveries.
Willie Lanier received All-Pro (AFL ALL-Star or All-AFC) mention every year, appearing in all-star games from 1968 to 1975 (his first two in the AFL and his last six in the AFC). In 1986 he achieved Pro Football Hall of Fame status.