Selected in the second round of the 1965 NFL draft, 18th overall, Jefferson spent his first five NFL seasons with the Pittsburgh Steelers. In 1968, Jefferson led the NFL in receiving yards with 1,074. His 58 receptions and 11 touchdowns were both 2nd highest in the NFL that season. He was named 1st Team All-Pro by Associated Press, the Newspaper Enterprise Association, New York Daily News and UPI in 1969. Jefferson finished that season with 67 receptions for 1,079 yards and nine touchdowns and became the first Steelers receiver to post back-to-back 1,000-yard seasons. Despite being the Steelers best offensive player, conflicts with head coach Chuck Noll as the team's player representative resulted in a trade to the Baltimore Colts in August 1970. With the Colts for only one season, Jefferson helped them reach and win Super Bowl V. He finished the 1970 regular season with 44 receptions for 749 yards and seven touchdowns. He caught a 45-yard touchdown pass from Johnny Unitas in the Colts 17-0 divisional playoff win over the Cincinnati Bengals and had three receptions for 52 yards in the Colts 16-13 victory over the Dallas Cowboys in the Super Bowl. Jefferson was traded to the Washington Redskins in 1971 for a first round draft pick in 1973. He spent six seasons with the Redskins under head coach George Allen, helping them reach Super Bowl VII in 1972, and retired after the 1976 season. Jefferson was named to the Pittsburgh Steelers Legends team in 2007, as one of the best 24 Steelers players prior to 1970.
After football
After his retirement from football, Jefferson has remained in the Washington, D.C. area. He had a leading role in the 1976 blaxploitationfeature filmBrotherhood of Death. In the ensuing years, his endeavors have included owning a chain of barbecue restaurants with the last closing in 1992 and owning a catering business. As of 2006, he was working in the real estate business. He reported that he and his wife, had three children and four grandchildren.
Personal
Jefferson is the cousin of tight end Marv Fleming; they were teammates in high school and college, but were on opposing sides during Super Bowl VII. Jefferson left Utah for the NFL in 1965, but returned to school in the off-seasons and completed his bachelor's degree in June 1970.