The CBS shows will collide in two nights of programming next week, which begins with NCIS characters Callen (O'Donnell) and Sam (LL Cool J) heading to Hawaii to stop a bioterrorism attack.
Hawaii Five-O leads Danny (Caan) and Chin Ho (Daniel Dae Kim) will then work with the team in LA the following episode.
"Daniel and Scott fit right in here," O'Donnell told TV Guide. "It is funny for me seeing unfamiliar faces in this room... And for us, it's strange to go to Hawaii and be playing the same characters, but the crew is completely different. It's kind of bizarro world."
Caan, meanwhile, said that he was initially uncertain about how the NCIS writers would cope with his character.
"There are parts of doing this that are weird," he confessed. "There are writers on our show who have written 40-something episodes, so they know my thing or Daniel's thing. And then we're gonna tell the NCIS: LA writers, 'Here, you give it a shot'.
"You can be skeptical about that. But I think it worked out really well. And when you're working with the same people over and over again, it is fun to work with new people - and having them be LL Cool J and Chris just makes it better."
Both shows were renewed for another season by CBS in March.
Hawaii Five-0 airs Monday at 10/9c, while the NCIS: LA crossover episode airs Tuesday at 9/8c.