Valderrama will play a once grounded NCIS field agent who accepted a deep cover assignment years ago and never resurfaced. Many agents aren't aware that he's still on the job or that he's even alive. With his return, his dedication to his job and country has left him an unpredictable loose cannon.
See images of Michael Weatherly:
Michael Weatherly (Photo by J. Vespa/WireImage)
Jessica Alba & Michael Weatherly (Photo by Steve Granitz/WireImage)
Michael Weatherly & Murray during The Lint Roller Party at Barker Hanger in Santa Monica, California, United States. (Photo by Gregg DeGuire/WireImage)
UNITED STATES - JULY 18: CBS Party at Dodger's Stadium - TCA Press Tour In Los Angeles, United States On July 18, 2004-Pauley Perrette and Michael Weatherly of 'NCSI,' at the CBS Party for Television Critics Association's (TCA) Press Tour. (Photo by Barbara BINSTEIN/Gamma-Rapho via Getty Images)
MONTE CARLO, MONACO - JUNE 30: US actor Michael Weatherly attends the photocall of 'Navy NCIS: Naval Criminal Investigative Service' during the 46th annual Monte Carlo Television Festival at the Forum Grimaldi, on June 30, 2006 in Monte Carlo, Monaco. (Photo by Francois Durand/Getty Images)
LOS ANGELES - AUGUST 1: 'Agent Afloat' -- The NCIS team (Michael Weatherly, left, Mark Harmon, center and Cote de Pablo, right) investigate a mysterious suicide aboard a carrier on NCIS Tuesday Sept. 30 (8:00-9:00PM, ET/PT) on the CBS Television Network. (Photo by Cliff Lipson/CBS via Getty Images)
VALENCIA, CA - SEPTEMBER 04: (L-R) Actors David McCallum, Lauren Holly, Pauley Perrette, Sean Murray, Cote de Pablo, Brian Dietzen, Mark Harmon and Michael Weatherly attend the NCIS 100th Episode celebration at the Valencia Studios on September 4, 2007 in Valencia, California. (Photo by Michael Buckner/Getty Images)
MELBOURNE, AUSTRALIA - MAY 06: Actor Michael Weatherly and his niece Alexandra arrive at the 2007 TV Week Logie Awards at the Crown Casino on May 6, 2007 in Melbourne, Australia. The annual television awards sees Australia's most popular television talent compete for the coveted awards, of which there are 11 Most Popular categories and 11 industry-voted Most Outstanding categories. (Photo by Patrick Riviere/Getty Images)
VALENCIA - NOVEMBER 19: 'Flesh and Bone'-- Gibbs questions DiNozzoÕs (Michael Weatherly, right) ability to do his job when the elder DiNozzo (special guest star Robert Wagner, left) becomes involved in their latest investigation, on ÒNCIS, Tuesday Jan.12 (8:00-9:00PM, ET/PT) on the CBS Television Network. (Photo by Sonja Flemming/CBS via Getty Images)
LOS ANGELES - OCTOBER 13: 'Child's Play'- The team (Michael Weatherly, Mark Harmon, Sean Murray, left to right) must put their Thanksgiving plans on hold when the horrific death of a Marine leads them to a government think tank that employs child prodigies, on NCIS, Tuesday Nov. 24 (8:00-9:00PM, ET/PT) on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
LOS ANGELES - JUNE 1: 'Jack Knife' - When a Marine is found dead, DiNozzo (Michael Weatherly) and the team hit the open road to bust an illegal trucking operation, on NCIS, Tuesday Feb. 9 (8:00-9:00PM, ET/PT) on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
(EXCLUSIVE, Premium Rates Apply) MONTE-CARLO, MONACO - JUNE 09: ***EXCLUSIVE ACCESS*** Actor Michael Weatherly attends the 'NCIS' portrait session at Grimaldi Forum during the annual Monte Carlo Television Festival on June 9, 2010 in Monte-Carlo, Monaco. (Photo by Francois G. Durand/WireImage)
LOS ANGELES - -OCTOBER 3: 'Enemies Foreign' -- DiNozzo (Michael Weatherly) and the team are assigned to protect Ziva's father, when his attendance at a NCIS conference leads to some unexpected surprises on 'NCIS,' Tuesday, November 16 (8:00-9:00 PM, ET/PT) on the CBS Television Network. (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES - JANUARY 9: 'Secrets' -- When a Navy captain is found dead with an unusual costume hidden under his uniform, NCIS uncovers a secret society of real-life super heroes and must track down the villain, on NCIS, Tuesday, Feb. 14 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Perrey Reeves (right) guest stars as Wendy Miller, DiNozzo's (Michael Weatherly, left) journalist ex-fiance. (Photo by Ron P. Jaffe/CBS via Getty Images)
LOS ANGELES - MARCH 11: 'Dead Reflection' -- The NCIS team (left to right: Cote de Pablo, Michael Weatherly and Mark Harmon) tracks a Navy lieutenant's killer after a Pentagon security camera reveals a petty officer committing the crime. Meanwhile, Gibbs announces that Agent Barrett and her team will take over the Port-to-Port serial killer case, on NCIS, Tuesday, April 12 (8:00-9:00 PM, ET/PT) on the CBS Television Network. (Photo by Sonja Flemming/CBS via Getty Images)
LOS ANGELES - JANUARY 11: (l-r); Michael Weatherly, Sean Murray and Pauley Perrette during the NCIS session at the CBS Winter Press Tour 2012, held on January 11, 2012 at The Langham Huntington Hotel in Los Angeles, CA. (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES - AUGUST 24: A petty officer is gunned down in a billionaire'Âs Ferrari and the investigation leads the NCIS team to discover a link to a man Gibbs was named after, on NCIS, Tuesday, Oct. 30 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Pictured left to right: Mark Harmon and Michael Weatherly (Photo by Sonja Flemming/CBS via Getty Images) *** Local Caption)
LOS ANGELES - APRIL 25: 'Till Death Do Us Part' -- Terrorism threatens to shake the foundations of the Navy and NCIS, when the team continues to be eluded by the newest member of the NCIS Most Wanted Wall. Meanwhile, Jimmy Palmer's destination wedding is impacted by the case, on the season finale of NCIS, Tuesday, May 15 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Pictured left to right: Cote de Pablo, Sean Murray and Michael Weatherly (Photo by Michael Yarish/CBS via Getty Images)
LOS ANGELES, CA - OCTOBER 16: Michael Weatherly visits 'Extra' at The Grove on October 16, 2012 in Los Angeles, California. (Photo by Noel Vasquez/Getty Images for Extra)
NEW YORK, NY - MAY 15: Actors Michael Weatherly, Cote de Pablo and Mark Harmon attend the 2013 CBS Upfront at The Tent at Lincoln Center on May 15, 2013 in New York City. (Photo by Jim Spellman/WireImage)
LOS ANGELES, CA - JANUARY 08: Actors Josh Holloway (L) and Michael Weatherly attend The 40th Annual People's Choice Awards at Nokia Theatre L.A. Live on January 8, 2014 in Los Angeles, California. (Photo by Jeff Kravitz/FilmMagic)
LOS ANGELES - AUGUST 27: 'Anonymous Was a Woman' -- Gibbs and McGee (Sean Murray, left) travel to Afghanistan when a murder case leads them to an Afghan women's shelter Mike Frank'Âs secretly supported for years, on NCIS, Tuesday, Oct. 15 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Also pictured: Michael Weatherly. (Photo by Sonja Flemming/CBS via Getty Images)
WEST HOLLYWOOD, CA - JULY 17: (L-R) Actors Michael Weatherly, Pauley Perrette and Brian Dietzen arrive at the CBS, The CW, Showtime & CBS Television Distribution 2014 Television Critics Association Summer Press Tour at Pacific Design Center on July 17, 2014 in West Hollywood, California. (Photo by Barry King/FilmMagic)
LOS ANGELES - NOVEMBER 10: 'Check' -- The NCIS team must investigate a series of crime scenes that appear to be copy-cats of previous cases, on NCIS, Tuesday, Jan. 6 (8:00-9:00 PM, ET/PT), on the CBS Television Network. Pictured left to right: Emily Wickersham and Michael Weatherly (Photo by Greg Gayne/CBS via Getty Images)
LOS ANGELES - AUGUST 26: 'Choke Hold' -- The Secretary of the Navy assigns the NCIS team to a joint terrorism task force after a Naval research scientist is murdered and the lead suspect is wanted by the Russian government. In order to get a jump on the case, Gibbs has DiNozzo (Michael Weatherly) run interference with the leader of the task force, FBI Agent Leia Pendergast, on NCIS, Tuesday, Oct. 14 (8:00-9:00 PM, ET/PT), on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
LOS ANGELES - NOVEMBER 20: 'Sister City: Part One' -- After the passengers and crew of a private plane traveling from New Orleans to Washington D.C. are lethally poisoned, all evidence points to the missing chef, Abby's brother, Luca (Tyler Ritter). Gibbs and the D.C. team work in conjunction with Pride and the New Orleans team to locate Luca and determine why a private tech company was targeted, on the first part of a special two-hour crossover event on NCIS, Tuesday, Jan. 5 (8:00-9:00 PM, ET/PT), on the CBS Television Network. Pictured left to right: Pauley Perrette and Michael Weatherly (Photo by Bill Inoshita/CBS via Getty Images)
LOS ANGELES, CA - FEBRUARY 07: (R) Actor Michael Weatherly and guest attend the Hennessy Toasts Achievements In Music on February 7, 2015 in Los Angeles, California. (Photo by Unique Nicole/WireImage)
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"Wilmer Valderrama will be able to flex his dramatic, physical and comedic talents in this classic NCIS role," said executive producer Gary Glasberg. "Fans are going to see him like they've never seen him before. This is going to be fun. We're thrilled he's coming aboard."
Valderrama recently starred in Fox's shortlived sci-fi dramaMinority Report and is best known for playing Fez on That's '70s Show. Previous TV credits include Grey's Anatomy, From Dusk Till Dawn and Awake.
Valderamma's casting comes one month after NCIS bid a bittersweet goodbye to Weatherly and his beloved character, Tony DiNozzo.
Ahead of the finale, Weatherly sat down with ET's Kevin Frazier, saying Tony's farewell "is a very emotional episode but it's also very uplifting." With NCIS behind him, the 47-year-old actor knew his time on the popular series had neared its end.
"The character had to leave at some point," Weatherly explained. "I should've left years ago, but I was having so much fun I overstayed my welcome horribly -- like that guest who won't leave and keeps digging into your fridge."
"After almost 6 loving and wonderful years together, we have decided to end our relationship," their joint statement began. "This was an incredibly difficult decision for both of us, but we have realized more than anything that we are better as best friends."
NCIS will air Tuesdays at 8 p.m. ET/PT this fall on CBS.