Mark Harmon returns full time for ‘NCIS: Origins’ season 3

The actor will appear in every episode as a present day Gibbs while continuing to narrate and executive produce

Mark Harmon is set to make his full time acting return to the NCIS franchise, with CBS confirming that he will appear in every episode of the third season of NCIS: Origins during the 2026 to 2027 television season.

The announcement marks Harmon's most substantial on screen involvement in the franchise since stepping away from the flagship NCIS series during its nineteenth season in 2021. While he has continued to serve as narrator and executive producer on NCIS: Origins, his acting appearances have so far been limited to the series premiere in 2024 and a special crossover episode during the second season.

For Season 3, however, Harmon will reprise his iconic role as Leroy Jethro Gibbs throughout the entire season. Rather than appearing in flashbacks, he will portray the present day version of Gibbs in a storyline that runs alongside the events of the prequel.

The new season will revolve around a present day mystery that connects directly to Gibbs' years at Camp Pendleton during the 1990s. The investigation will unfold across the entire season, linking Harmon's scenes with the younger version of Gibbs portrayed by Austin Stowell.

The approach represents a notable shift for the NCIS franchise. For more than two decades, the various series have largely relied on standalone procedural episodes, allowing viewers to watch individual stories without following an overarching narrative. The new season of NCIS: Origins will instead adopt a heavily serialised format, with one central mystery developing from the premiere through to the finale.

CBS announced Harmon's expanded role through its official social media channels, confirming that the actor will appear in every episode while continuing his duties behind the scenes as an executive producer.

Austin Stowell will continue leading the prequel's 1990s storyline as the younger Gibbs, portraying the future special agent during his early years with the Naval Investigative Service. The cast also includes Kyle Schmid, Mariel Molino, Tyla Abercrumbie, Diany Rodriguez and Caleb Foote.

Harmon first introduced audiences to Leroy Jethro Gibbs when NCIS premiered in 2003. Over more than 18 seasons, the character became one of the most recognisable figures in television crime drama, serving as the calm, disciplined leader of the Major Case Response Team. His departure early in the 2021 to 2022 season marked the end of an era for the long running series.

The success of NCIS: Origins brought Harmon back into the franchise in a different capacity. Ordered straight to series by CBS in 2024, the prequel explores Gibbs' early career while allowing Harmon to frame each episode through narration from the older version of the character.

Season 3 will significantly expand that concept by integrating present day Gibbs into an ongoing storyline rather than using him solely as a narrator. The dual timeline format will allow viewers to follow both the young investigator's experiences in the 1990s and the older Gibbs as he works to solve a mystery connected to his past.

Behind the camera, David J North returns as showrunner and executive producer. He is joined by executive producers Mark Harmon, Sean Harmon, Michele Greco and former NCIS: Los Angeles star Eric Christian Olsen.