The actress, who guest starred in three episode of the CBS long-running crime procedural, will reprise her ole of Kasie Hines. She was first introduced as Ducky's (David McCallum) new graduate assistant in Episode 17 and was then brought in by NCIS boss Gibbs (Mark Harmon) after Abby left the show to help out on a case.
Reasonover is a veteran of the CBS family with a background in comedy. The actress wrote and performed during the 2014 CBS Diversity Showcase and served as head writer in 2015.
Her acting credits include guest starring stints on CBS' 2 Broke Girls, Grace and Frankie, Superstore, Girl Meets World and Comedy Bang! Bang! She also co-starred on Clipped.
Reasonover's writing credits include the Emmy-nominated I Love You, America, I Love Dick, and Adam Ruins Everything. She is represented by CAA.
NCIS remains CBS' most popular drama series after 15 seasons. The latest season averaged 17 million viewers per episode.
Reasonover's new permanent gig comes as the series said goodbye to longtime series regular Perrette near the end of its 15th season, as well as the death of Clayton Reeves (Duane Henry).
The season finale also left another member of the team's life in the balance, with Leon Vance (Rocky Carroll). In the final scene of the finale, he was shown in the clutches of terrorists who committed several murders and torture in Afghanistan.
Reasonover joins the cast with Harmon, Carroll, McCallum, Sean Murray, Brian Dietzen, Emily Wickersham, Wilmer Valderrama and Maria Bello.
Valderrama recently secured his return to the CBS series as a regular, as well as a two-year first-look deal for his production company WV Entertainment.
"As someone who immigrated to the United States at 14 years old, I am immensely passionate about this opportunity to create engaging and culturally relevant projects with CBS Television Studios," Valderrama said at the time.
Valderrama stars as Special Agent Nick Torres on NCIS. He joined the show in season 14 and only signed a two-year deal. He signed another two-year pact Monday, keeping him on the Mark Harmon-starring show through season 17.
NCIS season 16 will premiere Tuesday, Sept. 25 at 8 p.m. ET on CBS, followed by the series premiere of FBI at 9 p.m. and the season premiere of NCIS: New Orleans at 10 p.m.