The No Good Deed star, 42, was sworn in during a special ceremony this week (begs21Sep15) and she later took to to share a photo of the proud moment.

The outspoken actress also took the opportunity to take a swipe at property tycoon-turned-politician Trump for his ill-advised comments about Mexican immigrants in America, and vowed to use her new citizenship status to do all she can to keep him out of the White House ahead of the 2016 election.

She captioned the snap, "FYI (for your information), Donald Trump, I'm a new US citizen, I SPEAK OUT, and I don't support you... Fuerza Latina (Latin force)".

Del Castillo joins an ever-growing list of Latin celebrities who have spoken out against Trump, who suggested many Mexican immigrants were "rapists" who brought drugs and crime into the U.S. as he launched his bid for the White House in June (15).

Among those who have slammed Trump for his remarks include Eva Longoria, Ricky Martin, Marc Anthony, rapper Pitbull, comedian George Lopez and movie veteran Rita Moreno.