Voting for the Parliament was on the basis of universal suffrage, which comprised all nationals over 18 years of age, registered in Catalonia and in full enjoyment of their political rights.

The 135 members of the Parliament of Catalonia were elected using the D'Hondt method and a closed list proportional representation, with an electoral threshold of three percent of valid votes—which included blank ballots—being applied in each constituency.

Seats were allocated to constituencies, corresponding to the provinces of Barcelona, Girona, Lleida and Tarragona, with each being allocated a fixed number of seats:[1] In smaller constituencies, the use of the electoral method resulted in an effective threshold based on the district magnitude and the distribution of votes among candidacies.

[1] The president had the prerogative to dissolve the Parliament of Catalonia and call a snap election, provided that no motion of no confidence was in process and that dissolution did not occur before one year had elapsed since a previous one under this procedure.

The highest percentage figure in each polling survey is displayed with its background shaded in the leading party's colour.