Nealis began his career with local club Massapequa SC. He also played for Massapequa High School. As a sophomore in 2013, Nealis scored the winning goals in both the semi-final and final of the 2013 NYSPHSAA Class AA tournament where he was also named MVP.[2]
As a junior in 2014, Nealis' Massapequa team finished undefeated in the regular season. Their playoff run ended with a 2–0 loss to the Syosset Braves in the Nassau County Class AA tournament.[3]
In 2016, Nealis began his collegiate soccer career with the Georgetown Hoyas. In 2019, Nealis captained the Georgetown University team that won their first NCAA national championship.[4] Nealis was named the Defensive Most Outstanding Player of the national tournament,[5] becoming the first Hoya to win the honor.[6][7] During the 2019 season, Nealis was also named a finalist for the MAC Hermann Trophy, an annual award to the top college soccer player in the nation.[8]
On January 9, 2020, Nealis was selected by Inter Miami CF as the third overall pick in the 2020 MLS SuperDraft.[9] Nealis made his professional debut on September 23, 2020, appearing as a starter in a 1–4 loss to New York Red Bulls. He ended his first season appearing in 20 matches for Inter Miami.
On April 11, 2021, Nealis was traded to Nashville SC in exchange for $175,000 in general allocation money and an additional $50,000 if he was to meet certain performance-based metrics.[10] On April 24, 2021, Nealis made his debut with Nashville, appearing an injury-time substitute in a 2–2 draw with CF Montréal. On July 17, 2021, he started his first match for the club, recording an assist in a 5–1 victory over Chicago Fire FC.[11]
On December 16, 2021, Nealis was traded to New York Red Bulls in exchange for $175,000 in general allocation money and an additional $75,000 if he was to meet certain performance-based metrics.[12] On February 26, 2022, Nealis made his debut for New York, appearing as a starter in a 3–1 victory over San Jose Earthquakes in the opening match of the season.[13] On May 25, 2022, Nealis scored his first goal as a professional in a 3–1 victory for New York over Charlotte FC as his team advanced to the quarterfinals of the 2022 U.S. Open Cup.[14] In November 2023, Nealis signed a new contract with Red Bulls to remain through the 2024 season.[15]
