Largent was immediately picked up by the Seattle Seahawks, a new franchise with an assistant coach, Jerry Rhome, who had previously coached Largent at the University of Tulsa. Rhome helped to instill confidence in Largent, who made his NFL debut in a 1976 game against the St. Louis Cardinals with five receptions. Largent ended up being the Seahawks' most reliable receiver in his fourteen years with the team. Although his opponents typically dismissed him as slow and slight of stature, Largent ended up exceeding 1,000 yards in receptions in eight seasons between 1978 and 1986. Unfortunately, the Seahawks never claimed an NFL championship during Largent's years with the team, which ended in 1989.
Perhaps Largent's finest moment came in a December 10, 1989 game against the Cincinnati Bengals, when he broke the existing record for touchdown receptions. Largent ended his career at the end of that season as the holder of the NFL records for most receptions (819), yards (13,089), and touchdowns (100). He also held the record for receptions in the most consecutive games (177) during his career, a title that was later claimed by Jerry Rice.
After retiring as a professional athlete, Largent moved back to Tulsa with his wife, the former Terry Bullock, whom he had married in January 1975. The Largents had four children—a daughter, Casie Lee, and three sons, Kyle, Kelly, and Kramer. Largent opened an advertising and marketing consulting firm in Tulsa after returning to the city, but he remained a popular sports personality in Seattle, where he often appeared at political fundraisers for Republican candidates. Largent also cultivated ties to the Republican Party in Oklahoma and in 1994 opened up his own campaign for the U.S. House seat from the First District. Running as a conservative in a heavily Republican state, Largent took the election with sixty-three percent of the vote.