According to Fox Sports and the NFL Network, Spagnuolo was informed of the decision Monday morning, one day after the Rams completed a dismal 2-14 campaign.
Spagnuolo finished his brief tenure with a mark of 10-38. The Rams were 1-15 in his first year, then took a big step forward at 7-9 in 2010 before regressing this season.
This year's team was expected to contend in the NFC West, but started with six straight losses and never recovered. The Rams' lone wins came against New Orleans and Cleveland in a three-week span, and they finished the year with a seven-game losing streak.
Spagnuolo was named the Rams coach in January 2009 after spending two years as defensive coordinator for the Giants. He helped New York to a Super Bowl title after the 2007 season and could again draw interest from teams looking for a defensive coordinator.