Wilkens was a two-time All-American (1959 and 1960) at Providence College. He led the team to their first NIT appearance in 1959, and to the NIT finals in 1960. When he graduated, Wilkens was, with 1,193 points, the second-ranked scorer in Friar history (he has since dropped to twentieth as of 2005). In 1996, Wilkens' No. 14 jersey was retired by the college, the first alumnus to receive such an honor. In honor of his collegiate accomplishments, Wilkens was one of the inaugural inductees into the College Basketball Hall of Fame in 2006.
Wilkens was drafted sixth overall by the St. Louis Hawks in the 1960 NBA Draft. He began his career with eight seasons with the St. Louis Hawks, who lost the finals to the Boston Celtics in his rookie season. The Hawks made the playoffs consistently with Wilkens but never again reached the finals. Wilkens placed second to Wilt Chamberlain in the 1967–1968 MVP balloting, his last with the Hawks.
Wilkens was traded to the Seattle SuperSonics for Walt Hazzard and spent four seasons there. He averaged 22.4 points, 6.2 rebounds, and 8.2 assists per game in his first season for the SuperSonics, and was an All-Star in three of his seasons for them. He was named head coach in his second season with the team. Although the SuperSonics did not reach the playoffs while Wilkens simultaneously coached and started at point guard, their record improved each season and they won 47 games during the 1971–72 NBA season. Wilkens was dealt to the Cleveland Cavaliers before the start of the next season in a highly unpopular trade, and the SuperSonics fell to 26-56 without his leadership on the court.
Wilkens scored 17,772 points during the regular season, was a nine-time NBA All-Star, and was named the 1971 NBA All-Star Game MVP in 1971. With Seattle, he led the league in assists in the 1969–70 season, and at the time of his retirement was the NBA's second all-time leader in that category, behind only Oscar Robertson.
From 1969–1972 with Seattle, and in his one season as a player with Portland, he was a player-coach. He retired from playing in 1975 and was the full-time coach of the Trail Blazers for one more season. After a season off from coaching, he again became coach of the SuperSonics when he replaced Bob Hopkins who was fired 22 games into the 1977–1978 season after a dismal 5-17 start. The SuperSonics won 11 of their first 12 games under Wilkens, made the playoffs, and ultimately reached the 1978 NBA Finals before losing in seven games to the Washington Bullets.
He coached in Seattle for eight seasons (1977–1985), winning his (and Seattle's) only NBA Championship in 1979. He would go on to coach Cleveland (1986–1993), Atlanta (1993–2000), Toronto (2000–2003) and New York (2004–2005).
The Hall of Famer was named head coach of the New York Knicks on January 15, 2004. After the Knicks' slow start to the 2004–2005 season, Wilkens resigned from the team on January 22, 2005.
On November 29, 2006 he was hired as vice chairman of the Seattle SuperSonics' ownership group, and was later named the Sonics' President of Basketball Operations on April 27, 2007. On July 6, 2007 Wilkens resigned from the Sonics organization. Wilkens currently is seen on Northwest FSN Studio as a College Hoops analyst and occasionally appears on College Hoops Northwest at game nights. He is the founder of the Lenny Wilkens Foundation for Children.
"I learned my basketball on the playgrounds of Brooklyn. Today, being a playground player is an insult. It means all you want to do is go one-on-one, it means your fundamentals stink and you don't understand the game. But the playgrounds I knew were tremendous training grounds."
"Show people how to have success and then you can push their expectations up."