Turning down other notable offers, Biletnikoff chose to attend Florida State University in Tallahassee. He missed several games during his first varsity season in 1962 with a broken foot. He played on both sides of the ball his junior season, leading the team in receptions and interceptions. That year, he returned an interception 99 yards for a touchdown off a pass thrown by George Mira of the Miami Hurricanes, a record which stood until 1987, when Deion Sanders broke it by one yard. As a senior in 1964, Biletnikoff led the nation with 1,179 receiving yards and 15 touchdowns, and finished second in receptions (70) and scoring (90). One of his touchdowns came in the first quarter against the Florida Gators, which helped the Seminoles earn their first victory in the in-state rivalry, 16–7. The Seminoles finished the year with a 36–19 victory over Oklahoma in the Gator Bowl, in which Biletnikoff set school records with 13 receptions for 194 yards and four touchdowns. He was a consensus pick for the 1964 College Football All-America Team, receiving first-team honors from four official selectors: the Associated Press, Central Press Association, Football Writers Association of America, and Newspaper Enterprise Association. He was Florida State’s first consensus All-American in football. Biletnikoff compiled 100 receptions for 1,655 yards and 20 touchdowns in his career with the Seminoles, which at the time were all school records. While in college Fred also joined the Lambda Chi Alpha fraternity.

After graduating from FSU, he was selected by the Oakland Raiders in the second round of the 1965 AFL Draft, 11th overall and by the Detroit Lions in the third round of the 1965 NFL Draft, the 39th overall selection. Biletnikoff signed with the Raiders, where he played for fourteen seasons. With Oakland, he was nicknamed “Coyote”, and “Doctor Zhivago” because of his Russian heritage. In 1966, he caught his first touchdown pass, thrown by quarterback Tom Flores, who later became the Raiders’ head coach the season after Biletnikoff was released by the team.

In his rookie season, Biletnikoff played primarily on special teams. He did not see playing time on offense until the seventh game of the year, against the Boston Patriots, in which he caught seven passes for 118 yards. His production increased significantly with Oakland’s acquisition of quarterback Daryle Lamonica in 1967. That year, he caught 40 passes for 876 yards and five touchdowns and led the league with an average of 21.9 yards per reception. He was invited to play in the 1967 AFL All-Star Game. In that year’s AFL championship game, Biletnikoff had two receptions for 19 yards in the Raiders’ 40–7 blow-out win over the Houston Oilers. In Super Bowl II against the Green Bay Packers, he caught two passes for 10 yards as the Raiders were defeated 33–14.

Biletnikoff recorded his only 1,000-yard receiving season in 1968, when he caught 61 passes for 1,037 yards and six touchdowns. The following season, in 1969 he caught a career-high 12 receiving touchdowns. He was an AFL All-Star for the second time and earned first-team All-AFL honors from the Associated Press, the Newspaper Enterprise Association, Pro Football Writers of America, The Sporting News, Pro Football Weekly, and the New York Daily News. The AFL merged into the National Football League in 1970. In his first five seasons in the NFL, Biletnikoff was invited to four Pro Bowls.

A highly productive receiver in the postseason, Biletnikoff left the NFL as the all-time leader in postseason receptions (70), receiving yards (1,167), and receiving touchdowns (10) accumulated over 19 postseason games. He recorded over 100 receiving yards in a postseason five times. In the 1968 American Football League playoffs, he had 14 receptions for 370 yards and four touchdowns through two games. In the 1976–77 NFL playoffs, Biletnikoff recorded 13 receptions for 216 yards and a touchdown. This included four catches for 79 yards to set up three Oakland scores in the Raiders’ 32–14 victory in Super Bowl XI, for which he was named Super Bowl MVP.

Biletnikoff was released by the Raiders prior to the 1979 season. After a year off, he played one season in the Canadian Football League for the Montreal Alouettes in 1980. In his lone CFL season, Biletnikoff caught 38 passes, second-most on the team, for 470 yards and four touchdowns.

Biletnikoff popularized the use of Stickum, an adhesive that many players applied to their hands to assist with catching and gripping the ball. He would apply the substance all over his body and uniform prior to a game, a practice that was later picked up by Raiders cornerback Lester Hayes after Biletnikoff introduced him to it. The use of Stickum was banned by the NFL in 1981.

Biletnikoff was inducted into the Pro Football Hall of Fame in 1988. In 1999, Biletnikoff was ranked number 94 on The Sporting News’ list of the “100 Greatest Football Players”. He was voted into the College Football Hall of Fame in 1991. The Fred Biletnikoff Award, awarded annually by the Tallahassee Quarterback Club Foundation to the nation’s outstanding receiver in NCAA Division I FBS since 1994, is named in his honor. In 2016, Biletnikoff was named the Walter Camp Man of the Year by the Walter Camp Football Foundation in recognition of his public service and his contributions to football.

In February 1999, Biletnikoff’s daughter, Tracey, was found strangled to death at age 20 in Redwood City, California. Tracey’s boyfriend, Mohammed Haroon Ali, was convicted of first-degree murder in 2012 after admitting he strangled her with a T-shirt at a drug and alcohol treatment center during an argument over whether he had relapsed. He was sentenced to 55 years to life imprisonment. Biletnikoff called Ali an “animal” after the sentencing, and said his hatred for him would never go away. In 2015, Biletnikoff founded Tracey’s Place of Hope in Loomis, California, a shelter for domestic violence victims and substance abuse treatment for females ages 14 to 18.

Biletnikoff began his career in coaching soon after his retirement from playing. He served on the coaching staff of Orange Glen High School (1982), Palomar College (1983), Diablo Valley College (1984), Oakland Invaders (1985), Arizona Wranglers (1986), and Calgary Stampeders (1987–88). In January 2007, Biletnikoff retired as the wide receivers coach for the Oakland Raiders, which had been his role for 18 seasons starting in 1989.