Jefferson was with the Colts for only one season, but 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. He spent six seasons with the Redskins, helping them reach Super Bowl VII in 1972, before retiring after the 1976 season.
Jefferson had a leading role in the 1976 blaxploitation feature film Brotherhood of Death. After his retirement from football, he remained in the Washington, D.C. area. In the ensuing years, his endeavors have included owning a chain of barbecue restaurants and working for charities. As of 2006, he was working in the real estate business. He reported that he and his wife had three children and four grandchildren.