Has an NFL game ever ended 21-18?
It has. 21-18 has been a NFL final 18 times in 18,234 games. The first was Indianapolis Colts beat St. Louis Rams on October 1, 1995; the latest was New York Giants beat Los Angeles Chargers on September 28, 2025.
That makes 21-18 the 273rd most common final score out of 1,095 that have ever occurred in NFL. One point away, 22-18 has happened 1 times and 21-19 has happened 30 times.