Romero's first professional club were Acassuso of Primera B Metropolitana, making thirty-two appearances in his debut season while scoring four times; including his first against Colegiales.[3] In total, he appeared in seventy-eight league fixtures for Acassuso between 2011–12 and 2014.[1]
On 10 January 2016, Romero completed a permanent transfer to fellow Primera División side Argentinos Juniors.[1][4][5]
Argentinos were relegated to Primera B Nacional in his first season, he subsequently scored fifteen goals in forty-two matches in Primera B Nacional to help the club regain top-flight football for 2017–18.[1]
Independiente
On 30 December 2017, Romero completed a transfer to Independiente.[6] His first appearance for Independiente came versus Estudiantes on 29 January 2018, with his first goal arriving on 5 March against San Martín.[1]
Athletico Paranaense (loan)
February 2019 saw Romero move to Brazil's Athletico Paranaense on loan.[7] After a debut in a loss versus Fortaleza, he netted for the first time in Série A on 20 July in a four-goal win away to CSA.[1]
On 16 January 2021, Romero scored a hat-trick as Defensa y Justicia defeated Coquimbo Unido in the Copa Sudamericana semi-finals; taking his tally in the competition for the club to nine goals in eight games.[1] He then netted in the final against Lanús on 23 January, with Defensa defeating their domestic rivals to win their first Sudamericana title; the centre-forward finished as the top scorer with ten goals.[1]
River Plate
On 7 July 2021, River Plate signed Romero on a three-and-a-half-year contract to replace the recently transferred Rafael Santos Borré.[9]