Celebrity Insider reports that Harmon previously stated that he continues to love starring in the series, which the outlet takes as a "promising sign" of his continued involvement.
In addition, Harmon appeared briefly in a set video shot by co-star Wilmer Valderrama, with the veteran star thanking fans for their continued support of NCIS.
View this post on Instagram
Thank you from the cast of #NCIS currently on set after hearing about a season 17 pickup!!! Thanks to @wilmervalderrama for the video! ・・・ This is NOT a DRILL! Season 17.. OFFICIALLY a GO. So proud of our family and crew.. and to you the fans and supporters! We LOVE you! #NCIS
Following the announcement that NCIS would be returning for a 17th season, CBS Entertainment president Kelly Kahl issued a statement saying, "NCIS has been a global juggernaut for almost two decades. Its viewers are clearly the most loyal of any drama on television. They are passionate about the characters, the plot lines, and the storytelling."
"We owe a huge debt of gratitude to the gifted production team, and the cast, led by the extraordinary Mark Harmon. We are delighted that the show will remain a linchpin of the CBS schedule this coming season," Kahl added.
Notably, it appears that Harmon renews his NCIS contract yearly, as opposed to renewing for multiple years at one time. This is not an uncommon for actors to do, but it does have the potential to imply that the series could end fairly quickly, or least lose its main star.
Harmon is clearly a beloved actor at CBS, though, as Kahl publicly praised the star when he renewed his contract in 2018, which could indicate that they are prepared to keep him happy for as long as it takes.
"It's pretty simple – viewers everywhere love NCIS," Kahl said prior to the current 16th season. "This show speaks to viewers of all ages, in all parts of the country and around the world."
"NCIS' amazing characters and terrific storytelling result in some of TV's most passionate fans. Of course, none of this would be possible without an outstanding production team, and talented cast led by the incomparable and absolutely tireless Mark Harmon," he went on to say.
"We're thrilled he is returning as the centerpiece of the show, and we could not be more excited for NCIS 16th season," Kahl concluded.
NCIS airs on Tuesdays at 8 p.m. ET on CBS.