Ngata injured his right knee early in last Sunday's game against the Cincinnati Bengals but he returned to play. With Ngata not playing, Terrence Cody is expected to start at nose tackle for the Ravens.
This is only the third game Ngata has missed since 2010.
The other notable inactive for the Ravens is starting wide receiver Marlon Brown, who leads the team with five touchdown catches. Brown was added to the injury report Friday when he didn't practice because of a knee injury.
The Ravens have been using three wide receivers as their primary formation for the previous two games. Tandon Doss will likely see more time alongside Torrey Smith and Jacoby Jones.