Born in Morristown, New Jersey, Quinn grew up in nearby Morris Township and played high school football at Morristown High School in Morristown, from which he graduated in 1989. He attended Salisbury State University (now Salisbury University), an NCAA Division III school, and played on its football team as a defensive lineman from 1990 to 1993. He was a four-year starter in football and track and field and was named All Mason-Dixon in 1994 for his record breaking hammer throw (168.8 feet) while representing Salisbury State in the NCAA track championships that year as well. Dan was a two-time football team captain and captained the track and field team in 1994. After the 1993 football season, Quinn was co-awarded the prestigious Bobby Richards award. Quinn was inducted in the Salisbury University athletics Hall of Fame in 2005.
Quinn began his collegiate coaching career with the William & Mary Tribe football team in 1994 and at Virginia Military Institute in 1995, working with their defensive lines.
Quinn began his NFL coaching career in San Francisco as their defensive quality control coach in 2001. Quinn spent six years coaching the defensive lines for the San Francisco 49ers (2003–2004), the Miami Dolphins (2005–2006), and the New York Jets (2007–08). Quinn joined the Seattle Seahawks on January 12, 2009, but also served as the defensive coordinator for the Florida Gators during the 2011 and 2012 seasons, before returning to the Seahawks on January 17, 2013, to replace Gus Bradley, who became the Jacksonville Jaguars head coach. Quinn was a 2012 finalist for the Broyles Award, given annually to the nation's top assistant coach.
In Quinn's first season as defensive coordinator, the Seahawks led the league in fewest points allowed, fewest yards allowed, and takeaways with 231, 4,378, and 39, respectively, to become the first team since the 1985 Chicago Bears to accomplish the feat; the Seahawks went on to win Super Bowl XLVIII.
On February 2, 2015, Quinn reached an agreement to become the head coach of the Atlanta Falcons. On September 14, Quinn won his first game as the head coach of the Falcons, when his team beat the visiting Philadelphia Eagles 26–24. The Falcons got off to a 5–0 start in Quinn's first season, but finished the season 8–8 and missed the playoffs.
In the 2016 season, Quinn's Falcons finished the year with an 11–5 record, which was good enough to win the NFC South and clinch a first-round bye in the playoffs. In the divisional round, the Falcons defeated Quinn's former team, the Seattle Seahawks, 36–20, advancing to the NFC Championship for just the fourth time in franchise history.
On January 22, 2017, Quinn's Falcons won the NFC Championship against the Green Bay Packers 44–21, clinching a berth to play in Super Bowl LI against the New England Patriots. Up 21–3 at halftime and 28–3 in the third quarter, the Falcons lost the game in overtime by a score of 34–28.
NFL head coaches under whom Quinn has served:Steve Mariucci: San Francisco 49ers (2001–2002)
Dennis Erickson: San Francisco 49ers (2003–2004)
Nick Saban: Miami Dolphins (2005–2006)
Eric Mangini: New York Jets (2007–2008)
Jim L. Mora: Seattle Seahawks (2009)
Pete Carroll: Seattle Seahawks (2010, 2013–2014)
Assistant coaches under Quinn who have become NFL head coaches:Kyle Shanahan San Francisco 49ers (2017-present)