He was a member of the municipal council in Pineda de Mar from May 2011 to April 2018 and was appointed Vice President and Minister of Economy and Finance of Catalonia in June 2018.

[1][2] His grandfather Josep Aragonés i Montsant [es], a textile businessman and real estate tycoon, also served as the mayor of his hometown during the Francoist dictatorship, continuing in the post throughout the Transition as a member of Democratic Reform of Catalonia and People's Alliance up until 1987.

[31] On 21 May 2021, after the 2021 Catalan elections and an agreement with Junts, he became the first President of Catalonia from Esquerra Republicana since Josep Tarradellas in the 1980s.

[32] In June 2021, he welcomed the decision by Pedro Sánchez to pardon those convicted for the 2017 independence attempt but said that he would pursue amnesty for all those involved in that year's events, which would benefit over 3,000 people.

[33] Among the many measures, a "dialogue table" between the Catalan and Spanish governments to advance in the resolution of the political conflict was announced, though it would later go on to prove little to no effective.

In October 2022, the coalition government collapsed mainly due to internal skirmishes over the strategy to achieve independence between the two ruling coalition parties that had been brewing during all that year, leaving ERC with a minority government with the external support of the Socialists' Party of Catalonia.

In March 2024, he called for a snap election after the Parliament of Catalonia failed to pass the Government's yearly budget.

The pro-independence camp would go on to lose parliamentary majority for the first time since 2012, with Aragonès announcing his retirement from politics the day after the election.