Novillo played for Belgrano at youth level, notably being selected as part of their squad for the 2016 Torneo di Viareggio in Italy.[4][5] He was moved by Diego Osella into his senior squad after the 2018–19 Primera División's mid-season break, subsequently appearing for his senior bow in a goalless draw in the league with Unión Santa Fe on 27 January 2019; he participated in the full ninety minutes, picking up a yellow card in the process.[3][6]
Once returning from a loan spell at Racing Club in 2021, Novillo was sent out on loan once again in January 2022, this time to Colón until the end of the year.[7]
On 2 January 2023, Novillo signed for Huracán on a season-long loan from Belgrano, with a future option to make the move permanent.[8]
On 14 August 2023, Belgrano sent Novillo on a season-long loan to Primeira Liga side Vizela.[9]
^"Joaquín Novillo, quinto refuerzo" [Joaquín Novillo, fifth reinforcement]. cahuracan.com (in Spanish). 2 January 2023. Retrieved 27 August 2023.
^"Joaquín Novillo reforça defesa" [Joaquín Novillo reinforces defense]. fcvizela.pt (in European Portuguese). 14 August 2023. Retrieved 27 August 2023.