Along with fellow expansion team the Tampa Bay Buccaneers, the Seahawks began play in 1976. After an initial season in the NFC followed by a move to the AFC in 1977, the Seahawks recorded their first winning season in 1978, earning head coach Jack Patera NFL Coach of the Year honours. The early Seahawks teams were led by quarterback Jim Zorn, running back Curt Warner, and wide receiver Steve Largent, who retired as the NFL's all-time leading receiver and in 1995 was the first Seahawk inducted into the Pro Football Hall of Fame. In 1983 head coach Chuck Knox led the Seahawks to the AFC championship game in his first season with the team, and over the next nine years he posted a record of 83 wins and 67 losses. The Seahawks had their worst season in franchise history after Knox left in 1991, winning only two games that season. The following years saw many seasons of on-field struggle as well as off-field controversy, as team majority owner Ken Behring announced plans to move the team to Los Angeles in 1996, citing as the reason the condition of the team's home stadium, the Kingdome.

In 1997 billionaire Microsoft (Microsoft Corporation) cofounder Paul Allen purchased the Seahawks and helped push through public funding for a new football stadium, which kept the team in Seattle. Allen hired Mike Holmgren as head coach and general manager in 1999. In 2000 the team drafted running back Shaun Alexander (Alexander, Shaun) and the following year traded for quarterback Matt Hasselbeck, who, along with All-Pro offensive lineman Walter Jones, formed the core of the most successful team in Seahawks' history. After 25 seasons playing in the AFC, the Seahawks moved to the NFC in 2002 as part of an NFL realignment. The Seahawks made the play-offs in five of their first six seasons in the NFC. In 2006 the franchise made its first trip to the Super Bowl, which the team lost to the Pittsburgh Steelers.