She was first noticed for her role in The Magic of Belle Isle (2012), opposite Morgan Freeman, and is known for the 2014 film adaptation of the musical Annie, where she played Mia Putnam.

[citation needed] In 2013, Pierini was featured in episodes of Law & Order: Special Victims Unit, Golden Boy and Blue Bloods, as well as the Joey Dedio film Tio Papi.

[5] In September 2013, Pierini was announced as a castmember for the 2014 adaptation of the musical Annie opposite Jamie Foxx, Quvenzhané Wallis and Cameron Diaz.

[3] On the film's soundtrack, Pierini sung three songs, "Maybe", "It's the Hard Knock Life", and back-up vocals in the reprise of "Tomorrow".

Pierini's brother Anthony is a Broadway actor, appearing as an alternate in the productions of Mary Poppins from 2012–13, the 25th anniversary U.S. national tour Les Misérables from 2011–12 and Big Fish in 2013.