Tarkenton also founded Tarkenton Software, a computer-program generator company, and he toured the U.S. promoting CASE (computer-aided software engineering) with Albert F. Case, Jr. of Nastec Corporation. Tarkenton Software later merged with KnowledgeWare (with Tarkenton as president), until selling the company to Sterling Software in 1994.
Also, in Tarkenton's early years he was a member of the Masonic Youth Group DeMolay.
Tarkenton's first marriage was to Anna Elaine Merrell of Decatur, Georgia. They wed on December 22, 1960, at First Baptist Church in Decatur.
Tarkenton, his second wife Linda Sebastian Tarkenton (a former Eastern Airlines flight attendant), and four children and ten grandchildren currently reside in Atlanta, Georgia. They spend time at their mountain home located on the shores of Lake Burton in Rabun County, Georgia, and play golf at Waterfall Country Club, which overlooks Lake Burton and the surrounding mountains. They also spend part of their summer in Pebble Beach golfing.
The Minnesota Vikingsdrafted Tarkenton in the third round of the 1961 NFL Draft, and he was picked in the fifth round of the 1961 AFL draft by the Boston Patriots. He signed with the Vikings. Tarkenton, 21, played his first National Football League game (and the Vikings' first game) on September 17 against the Chicago Bears and led the Vikings to a victory by passing for 250 yards and four touchdown passes and ran for another as the upstarts stunned the Bears 37–13. He is the only player in NFL history to pass for four touchdowns in his first NFL game.
He played for the Vikings from 1961 to 1966, during which time he frequently locked horns with head coach Norm Van Brocklin, who disdained the idea of a mobile quarterback, a concept that Tarkenton dramatically advanced in the NFL. Tarkenton was given the nicknames "The Mad Scrambler," "Frantic Fran," and "Scramblin' Fran" because he frequently ran around in the backfield to avoid being sacked by the opposition (among his other nicknames: "Sir Francis," used occasionally by Howard Cosell of ABC Sports).
Tarkenton was traded to the New York Giants in 1967 (for two first round, and two second round draft picks) and played there for five seasons. His efforts helped the Giants rally from the NFL's basement (a 1-12-1 record in 1966) to better times. In the first game of the 1969 season, Tarkenton's Giants played the Vikings. After trailing 23-10 in the fourth quarter, Tarkenton threw two touchdown passes to secure a 24-23 comeback victory over his former team. The 24 points allowed by Minnesota's defense would be a season-worst for the unit that would finish #1 in dominant fashion.
Tarkenton was traded back to Minnesota in 1972, for three players plus a first and second round draft choice. He led the Vikings to three Super Bowls in the 1970s, but lost all of them. In Tarkenton's first Super Bowl appearance they lost to the Miami Dolphins 24–7 in Houston, they lost the second to the Pittsburgh Steelers in a defensive struggle 16-6 in New Orleans, and in the last Super Bowl Tarkenton would ever play, the Vikings were blown out by the Oakland Raiders 32-14 at the Rose Bowl in Pasadena.
Tarkenton won the NFL's MVP award after the 1975 season, capturing All-Pro honors in the process. Tarkenton was also second Team All-Pro in 1973 and earned All-NFC selection in 1972 and 1976. He was named second Team All-NFC in 1970 and 1974. Tarkenton was selected to play in nine Pro Bowls.
In his 18 NFL seasons, Tarkenton completed 3,686 of 6,467 passes for 47,003 yards and 342 touchdowns, with 266 interceptions. Tarkenton's 47,003 career passing yards rank him 6th all time, while his 342 career passing touchdowns is 4th all time in NFL history. He also is fifth on the all-time list of wins by a starting quarterback with 124 regular season victories. He also used his impressive scrambling ability to rack up 3,674 rushing yards and 32 touchdowns on 675 carries. During his career, Tarkenton ran for a touchdown in 15 different seasons, an NFL record among quarterbacks. He ranks fourth in career rushing yards among quarterbacks, behind Randall Cunningham, Steve Young and Michael Vick. He is also one of two NFL quarterbacks ever to rush for at least 300 yards in seven different seasons; the other is Tobin Rote. Inducted into the Pro Football Hall of Fame in 1986. Vikings head coach Bud Grant flatly called Tarkenton "the greatest quarterback who's ever played." When he retired, Tarkenton held NFL career records in pass attempts, completions, yardage, and touchdowns; rushing yards by a quarterback; and wins by a starting quarterback.
However, Tarkenton's poor performance in three Super Bowls and his inability to win a championship ring in 18 seasons prevents some people from considering him as great as other quarterbacks. Despite not winning a Super Bowl, he won six playoff games, and in 1999 he was ranked number 59 on The Sporting News list of the 100 Greatest Football Players. He was also known to heave the ball deep on third and long with no regard to an interception. He stated this was due to the great defense his teams had.
One of the more difficult losses of Tarkenton's career occurred during the 1975 NFC Divisional Playoffs. With what was considered by some observers to be the best team of their Purple People Eater era, the Vikings lost to the Dallas Cowboys 17-14 on a hail Mary touchdown pass from Dallas quarterback Roger Staubach to wide receiver Drew Pearson. The play so incensed the crowd that one fan fired a whiskey bottle from the stands, striking official Armen Terzian in the head. This was partly responsible for the banning of glass bottles at arenas around the country. Common Vikings folklore blames this incident for many future calls that referees made against the Vikings, and has been termed "Terzian's Revenge". Tarkenton also lost his father, who died while he was watching the game; it had been rumored that the "Hail Mary Pass" caused the cardiac arrest, but in fact Mr. Tarkenton died during the middle of the third quarter. It was a disappointing end to a spectacular season for the Vikings. They had finished the season with an NFC best 12-2 record and Tarkenton had won the NFL Most Valuable Player Award, and the NFL Offensive Player of the Year Award.
Tarkenton later appeared on the television show That's Incredible! and also worked part-time on Monday Night Football. He also guest-hosted Saturday Night Live on January 29, 1977.
A biography of Tarkenton titled Better Scramble than Lose was published in 1969. This followed Tarkenton's 1967 autobiography No Time for Losing and preceded by several years his 1977 autobiography Tarkenton co-written with Jim Klobuchar. The autobiographies chronicle not only his football career but also his personal evolution from his early football days as a preacher's son. Tarkenton wrote a book titled Broken Patterns: The Education of a Quarterback, as told to Brock Yates. It is a chronicle of the 1969 New York Giants season.
In 1986 Tarkenton, with author Herb Resincow, wrote a novel titled Murder at the Super Bowl, the whodunit story of a football coach killed just before his team is to participate in the championship game.
Tarkenton wrote the self-help, motivational books Playing to Win in 1984, and How to Motivate People: The Team Strategy for Success in 1986. He also wrote the motivational self-help business book titled What Losing Taught Me About Winning, and "Every Day is Game Day." In 1987, Tarkenton hosted a Think and Grow Rich TV infomercial that sold the book with an audio cassette version (the audio cassettes contained an introduction and conclusion by Tarkenton).
Tarkenton was also a pioneer in computer software, and founder of Tarkenton Software, a program generator company. He toured the United States promoting CASE or "computer-aided software engineering" with Albert F. Case, Jr. of Nastec Corporation, but ultimately merged his software firm with James Martin's KnowledgeWare, of which Tarkenton was president until selling the company to Sterling Software in 1994.
Since then, Tarkenton has been seen promoting various products and services including Tony Robbins and 1-800-BAR-NONE. He also founded GoSmallBiz.com, a small business consulting website, which is sold exclusively through Pre-Paid Legal Services, Inc. His most current company is an annuity marketing firm called Tarkenton Financial.
In 2009, Tarkenton made national news for his harsh criticism of Brett Favre's indecision on whether or not to come out of retirement to play for the Minnesota Vikings. Tarkenton, however, himself was similarly indecisive on his retirement during the last seven years of his playing career. Ironically, Tarkenton forced the Vikings to trade him away in 1967, even though head coach Norm Van Brocklin, with whom he had had much unhappiness, had already resigned. Tarkenton's departure caused the Vikings to go on a five-year search for a starting quarterback (Joe Kapp, Gary Cuozzo, Ron Vander Kelen, Norm Snead, and Bob Lee were all Vikings' starters between 1967 and 1971), before Tarkenton badgered the Giants into trading him back to the Vikings in 1972.
In February 2012, Tarkenton began hosting his own weekly call-in radio show on Sirius XM.