The French-born actor told People he was "happy" to have officially finished the naturalization process last week.
"[It was] such an emotional thing. I wasn't expecting it," he explained. "I cried about becoming an American. It's inexplicable the love I have for this country. I'm on cloud nine and I can't get down."
Marini also joked that while he loves American culture, he doesn't have any desire to sing the National Anthem at sporting events like other celebrities have done in the past.
"If you want it to snow in Los Angeles or rain for six months, let me sing the national Anthem," he quipped. "I could maybe train and try to be good at it – and I think it still wouldn't sound very good."
Marini is a married father of two children with wife Carole, who he wed in 1998.
He famously finished as runner-up in the 2009 season of Dancing with the Stars and also recently guest starred on Modern Family.