Milo Ventimiglia has opened up about the vows he and his on-screen partner Mandy Moore in the popular drama series, "This Is Us," took before the show premiered, and added they were still "very true" to it.

The 44-year-old actor appeared on "The Tonight Show Starring Jimmy Fallon" virtually Tuesday and praised his co-star Moore, who has played his on-screen wife Rebecca Pearson since season one dropped in 2016.

"Right before the show premiered, we were in New York for the upfronts and everybody was kind of milling about and Mandy and I were just kind of off to the side by ourselves," Ventimiglia recalled. "We just kind of raised our glasses to one another."

The official YouTube handle of the talk show shared the interview Wednesday.

"We almost took vows with one another where it was like, 'Hey, I promise to always communicate. I promise to not be happy until you're happy. I will always look out for you.' And we have stayed very true to what we said in the beginning," he said.

Ventimiglia also gushed over Moore, and said she has been working in front of the camera for over 26 years now and she is the "best partner" he ever had. The actor complimented Moore for her commitment, dedication and growth as an artist.

"The audience, you guys get to watch the show in its entirety," he explained. "I get to sit there in front of her, or stand in front of her, or lay in a bed next to her and watch front row what she does and how impactful it is, the work is to her. And I've only seen it grown."

Ventimiglia further added it has been a "pleasure" to work with the actress and act in her husband's role for six years. Moreover, considering this was going to be the last season, the actor noted he was excited to see what Moore was going to do next.

Moore, on the other hand, took to Instagram on Tuesday to share throwback photos of her and Ventimiglia on the sets of "This Is Us."

"Looking back at my first days on set of every season of #ThisIsUs," she captioned the post. "Gonna miss these days with the fam when it’s all over, but for now, we get to come together (virtually of course) and watch the premiere ep tonight!!!"

"This Is Us" airs every Tuesday at 9 p.m. ET on the NBC network.

Milo Ventimiglia
Milo Ventimiglia is not leaving “This Is Us” after Jack is killed. NBC