Campanella is of mixed Italian, Danish, and Lithuanian descent; her father's family originates in Naples, while her maternal grandfather emigrated from Espergærde in Denmark to the United States in the 1950s.

Campanella competed in the Miss New Jersey USA pageant twice, placing first runner-up in 2009, losing to Kaity Rodriguez[6] and in the top fifteen in 2010.

[7] On November 21, 2010, she competed in the Miss California USA pageant and won the title and was crowned by outgoing titleholder Nicole Johnson.

She is the second redhead (although she is naturally blonde) and the first Miss Teen USA first runner up to win the Miss USA title, as well as the first winner from the West Coast since Shannon Marketic won in 1992 also representing California and the first from the Western region since Brook Lee in 1997 who won representing Hawaii.

[12] In November 2011, Campanella traveled to the Bahamas to attend the Battle 4 Atlantis Basketball competition with several state titleholders about to compete at Miss USA 2012.

She also attended the Miss Nevada USA 2012 pageant in Las Vegas later that month, where she was a special guest at the grand opening of 1Oak at The Mirage.

On June 3, 2012, Campanella crowned Olivia Culpo as her successor in Las Vegas, who ultimately went on to win the title of Miss Universe.

[17][18] Campanella began modeling at age 16 in New York City and has appeared in Marie Claire, Allure, InStyle, Elle, and Women's Health magazines.

[20] In 2013, she posed partially nude, with three other Miss USA winners for a PETA anti-fur campaign to "put an end" to the use of fur coats as award prizes in pageantries.