Firmino was loaned to the team's USL League One side New England Revolution II for the 2020 season. He made his pro debut on July 25, 2020 against Union Omaha, playing the full game. He scored his first professional goal on August 15 in a 3-3 draw with North Texas SC.[3]
Following the 2020 season, New England opted to release Firmino.[4]
On 3 March 2022, Firmino moved to USL Championship side Atlanta United 2.[6] On March 23, 2023, Firmino signed a short-team deal with Atlanta United FC ahead of their MLS fixture with Columbus Crew.[7] On June 21, 2023, Firmino was signed to a short-term deal with Atlanta United FC ahead of their match with New York City FC.[8] Firmino would make his MLS debut when he was subbed on in the 87th minute. He would go on to score in the 90+5' to pull Atlanta United FC level in the match that would end in a 2-2 draw.[9]