Merolla was born in Buenos Aires, and joined Huracán's youth setup from Nueva Chicago.[2] Promoted to the main squad for the 2016 season, he was an unused substitute in two first team matches before leaving.
Merolla scored his first goal on 2 April 2017, netting his team's second in a 3–1 away success over Atlanta. He finished the season with three goals in 36 appearances as Deportivo Español reached the promotion play-offs but missed out after losing to eventual winners Deportivo Riestra.[4]
Merolla returned to Huracán in July 2018, but was not used by manager Gustavo Alfaro. He only made his first team – and Primera División – debut for the club on 10 March 2019, playing the full 90 minutes in a 3–1 home loss against San Martín de Tucumán;[6][7] it was his only league appearance of the campaign.
Merolla started to feature more regularly from September 2019, after manager Juan Pablo Vojvoda departed the club and interim Néstor Apuzzo took over; on 1 November, he renewed his contract until June 2023, with a US$ 20 million release clause.[8] He scored his first goal in the top tier (and for the Quemeros) on 24 March 2021, netting the equalizer in a 1–1 draw at Atlético Tucumán.
In February 2023, Merolla was separated from the first team squad after failing to agree to a contract renewal.[9]
^"Merolla se va a préstamo a Brown (PM)" [Merolla moves out on loan to Brown (PM)]. Club Atlético Huracán (in Spanish). 28 August 2017. Retrieved 13 March 2018.
^"Mala noche para debutar" [Bad night to debut] (in Spanish). Soy Quemero. 11 March 2019. Retrieved 28 February 2023.