Romero was in the youth ranks of Boca Juniors when he was a Sub 15, but could not continue at the club for a matter of paperwork, therefore he did not play for the Xeneize.
In October 2014, after his good performances in the knockout round of the Copa Sudamericana against Lanús Argentina, in which he scored three goals, he was said to be worth $3 to 6 million. He was targeted by major European clubs, such as Atlético Madrid.
Racing Club
On 28 January 2015, Romero was signed by Racing Club for $2.7 million. He debuted on 18 February against Deportivo Tachira in Copa Libertadores. On 13 March 2015, Romero scored his first competitive goal for the club against Club Atlético Colón. On 15 August 2015, Romero scored his second goal against Union de Santa Fe.
On March 18, 2024, he was announced by Botafogo with a contract until the end of the season.[4] The player received the number 70 shirt to play for the club.[5] On April 2, the Paraguayan was listed for the first time, for the match against Junior Barranquilla in the Libertadores.[6] The Paraguayan debuted against the Colombians at Nilton Santos. Romero entered in the 39th minute of the final stage, replacing Marlon Freitas.[7]
On May 13, 2024, after an act of indiscipline, Óscar Romero was cut[8] from Botafogo's trip to Peru, where the team would face Universitario in the fifth round of Group D of the Libertadores group stage. According to the specialized press, the midfielder took, along with clubmate Diego Hernández, women to the concentration after the match against Fortaleza.
The following day, the Paraguayan spoke out, saying he accepted Botafogo's punishment, but denied that he had taken women to the team hotel.[9]