The Emmy-nominated actor received the 2,482nd star at a ceremony on Hollywood Boulevard on Monday, in the same week NCIS began its 10th season.
"I'm really fortunate to get up every morning and go do a job I love going to," the 62-year-old said.
Harmon has played Leroy Jethro Gibbs in the CBS drama since 2003.
After a brief career as an American football player, Harmon has had a variety of roles in television, film and on stage and has been twice nominated for an Emmy award.
His first nomination came in 1977 for his portrayal of a wounded soldier in the TV movie Eleanor and Franklin: The White House Years.
In 2002 he received another nomination for his portrayal of Secret Service agent Simon Donovan in The West Wing.
"This is a long way from where I started," said Harmon at a ceremony whose attendees included CBS president Les Moonves.
"If this means anything to me, it represents longevity."
Harmon appeared in CBS medical drama Chicago Hope for four years and starred alongside Jamie Lee Curtis in the 2003 remake of Freaky Friday.
His other big-screen credits include Wyatt Earp, The Presidio and Stealing Home.
Mark Harmon, star of the hit US police drama NCIS, has become the latest celebrity to have a star dedicated to him on the Hollywood Walk of Fame.