Amir O'Neil was only three years old when he and his twin brother Amari first expressed an interest in acting. Born in Jacksonville, Florida in 2006, the pair would entertain their parents and six siblings with antics gleaned from shows on Nickelodeon and the Disney Channel, but it wasn't until they were seven years old that their interest turned professional. After signing with a talent agency, Amir and Amari booked a starring appearance together in a nationally broadcast commercial for Walmart in 2014.
By the following year, the O'Neil family had relocated to Southern California, and Amir and Amari were sharing the role of a young boy living in the segregated south for the TV movie "White Water" (TV One, 2015). This part would prove to be a pivotal one in the O'Neil twins careers, showcasing both their range and professionalism. By later that same year, Amir had struck out on his own, landing the role of young Darren Mann on the sitcom "Mann and Wife" (Bounce TV, 2015-17) all by himself. Quickly finding a niche in the realm of TV comedies, O'Neil would next pivot to playing the precocious Zack on the Marlon Wayans sitcom "Marlon" (NBC, 2017-) in 2017.