The Cowboys (8-8), with Kyle Orton filling in two days after Tony Romo had back surgery, lost to a division rival with a playoff berth on the line for the third consecutive year.
The Eagles (10-6) will play host to New Orleans a wild-card game Saturday night.
Dallas trailed 24-16 when Orton threw a 32-yard touchdown pass to Dez Bryant. Orton went back to Bryant for the two-point conversion, but the ball fell incomplete.
The Cowboys got another chance with a stop from their beleaguered defense, but Orton’s pass was intercepted by former Georgia standout Brandon Boykin on the first play to seal the win.
McCoy finished with 1,596 yards.
The last time Dallas made the playoffs was 2009, its first year in its shiny $1.2 billion stadium.