The ninth season of NCIS: Los Angeles premiered on October 1, 2017 on CBS for the 2017–18 television season, and concluded on May 20, 2018. The season contained 24 episodes and the series’ 200th episode. Nia Long joined the cast as Shay Mosley for the ninth season after Miguel Ferrer's death. The ninth season ranked 23 with a total of 10.50 million viewers.