The 1980Dallas Cowboys season was their 21st in the league. The team improved their previous output of 11–5, winning twelve games. They qualified for the playoffs as an NFC Wild Card, but lost in the Conference Championship.
The season featured a very unusual end to the regular season. Going into the final week of the season, Dallas (at 11–4) played Philadelphia (12–3) at Texas Stadium. Under the NFL's tiebreaking rules, if Dallas could beat the Eagles by 25 points, they would earn the NFC's number one seed and homefield advantage throughout the playoffs. However, if they lost (or won by less than 25) then Philadelphia would get the number one seed and (since they played in the same division) Dallas would be a wildcard team. Dallas led 35–10 in the fourth quarter, but the Eagles rallied to lose only 35–27. This forced Dallas to play an extra week in the playoffs and a road game in Atlanta in the divisional round. Dallas ultimately lost at Philadelphia in the NFC Championship game.