During the recruiting process, Dawson had to choose between Ohio State University and Purdue. While he was reluctant to take over Woody Hayes' split-T offense with the Buckeyes, the true reason for his selection of Purdue stemmed from the chemistry he had established with a Boilermaker assistant coach, Hank Stram, beginning a friendship that would last for more than a half century. During three seasons with the Boilermakers, Dawson threw for over 3,000 yards, leading the Big Ten Conference in that category during each campaign. While a student at Purdue, Dawson was initiated into the Alpha Tau Omega Fraternity.
As a sophomore in 1954, Dawson put together an outstanding first season as the NCAA's leader in pass efficiency, while also playing defense and serving as the Boilermaker kicker. Blessed with a strong offensive line, he threw four touchdown passes in a 31-0 victory over the University of Missouri, then later engineered a huge upset of the University of Notre Dame. The Fighting Irish had entered the contest in the midst of a 13-game winning streak.
Dawson looks for a receiver against Wisconsin, 1956
Despite his status as a first round draft pick, Dawson was unable to make an impact with the Pittsburgh Steelers. Following his rookie campaign, his status in the Steel City became even more tenuous when the Steelers acquired future Hall of Famer Bobby Layne. Failing to dislodge the colorful signal caller, Dawson was then traded to the Cleveland Browns on December 31, 1959.
After encountering similar problems in battling Browns' quarterback Milt Plum, Dawson was released, having completed only 21 passes for 204 yards and two touchdowns in his five seasons of NFL play. However, he soon found his calling when he signed with the American Football League's Dallas Texans on June 30, 1962. The move reunited him with Stram, who was beginning his third year as the Texans' head coach.
In that first season, 1962, Dawson led the league in touchdowns and yards per attempt, and was The Sporting News' selection as the AFL MVP, and was selected by his peers as a Sporting News1966 AFL All-League player. He also led them that year to the first of three league titles in a thrilling double-overtime victory over the two-time defending champion Houston Oilers. Dawson ran a ball-control offense in the 20-17 win, and tossed a 28-yard touchdown pass to halfback Abner Haynes. Then the team moved to Kansas City and were renamed The Chiefs in 1963.
A pinpoint passer, Dawson's mobility helped him flourish in Stram's "moving pocket" offense. He would win four AFL passing titles and was selected as a league All-Star six times, ending the 10-year run of the league as its highest-rated career passer. From 1962 to 1969, Dawson threw more touchdown passes (182) than any other professional football quarterback during that time. In 1966, Dawson led the Chiefs to a, 11-2-1 record and a 31-7 win over the Buffalo Bills in the AFL championship game, earning his team the honor of representing the AFL in Super Bowl I, the first championship game between the AFL and their NFL rivals. The NFL champion Green Bay Packers won easily, 35-10, but Dawson had a fairly good performance in the game, completing 16 of 27 passes for 210 yards and a touchdown, with 1 interception.
While he threw for more than 2,000 yards in each of the previous seven campaigns, Dawson's 1969 season with Kansas City would be his most memorable by making a dramatic comeback from a knee injury suffered in the season's second game. The injury was first feared as season-ending, but after missing five games, Dawson went on to lead the Chiefs to road playoff victories over both the defending champion New York Jets and the Oakland Raiders.
He then capped his year with MVP accolades in Super Bowl IV, the last game ever played by an American Football League team. In the game, Dawson paced the Chiefs to a win over the NFL's heavily favored Minnesota Vikings by completing 12 of 17 passes for 142 yards and a touchdown, with 1 interception, and rushing for 11 yards. The performance was especially notable given the fact that he had been linked to a gambling investigation (by an unrelated gentleman who was named Donald Dawson) in the days leading up to the game.
With the league's absorption into the National Football League in 1970, Dawson earned one final honor from the league as a member of the second team All-time All-AFL Team. He is also a member of the Chiefs' Hall of Fame and the Pro Football Hall of Fame. He would earn Pro Bowl honors following the 1971 NFL season, then ended his career in 1975, having completed 2,136 of 3,741 passes for 28,711 yards and 239 touchdowns, with 181 interceptions. He also gained 1,293 rushing yards and 9 touchdowns on the ground
On November 1, 1970, the Chiefs led the Oakland Raiders 17-14 late in the fourth quarter. Facing third and long, a run by Dawson apparently sealed victory for the Chiefs, but as Dawson lay on the ground, he was speared by Raiders’ defensive end Ben Davidson, who dove into Dawson with his helmet, provoking Chiefs’ receiver Otis Taylor to attack Davidson. After a bench-clearing brawl, offsetting penalties were called, nullifying the first down under the rules in effect at that time. The Chiefs were obliged to punt, and the Raiders tied the game on a George Blanda field goal with eight seconds to play. Taylor’s retaliation against Davidson not only cost the Chiefs a win, but Oakland won the AFC West with a season record of 8-4-2, while Kansas City finished 7-5-2 and out of the playoffs.
In 1966, while still playing for the Chiefs, Dawson became sports director at KMBC-TV in Kansas City. On March 16, 2009, Dawson announced he would step down from anchoring on a nightly basis. He will still report for KMBC during the Chiefs football season and will fill in when other anchors are on leave. Since 1985, Dawson has also been color analyst for the Chiefs radio broadcast team.
From 1977 to 2001, he served as the host of HBO's Inside the NFL, and also worked as an analyst for NBC's AFC coverage from 1977-1982.
In 1985, Dawson began serving as a color commentator for the Chiefs Radio Network. He currently works with Mitch Holthus and former Chiefs player Kendall Gammon.
Dawson is married to his second wife Linda, Dawson was married to his first wife Jackie from 1953 until her death in 1978 and has two grown children (Lisa Anne and Len, Jr.) from this marriage. He and his family live in Kansas City. Dawson is a seventh son of a seventh son. In 1991, Dawson was diagnosed with prostate cancer.