The data is based on all votes counted, according to DIP, which also noted that voter turnout was 21.35%, down from 29.85% in the previous European Parliament (EP) elections held in 2019.
HDZ won 34.60% of the votes, followed by the Social Democratic Party (SDP) and its partners with 25.96%, the eurosceptic and right-wing populist Homeland Movement (DP) with 8.82%, and the left-wing, green political party Mozemo (We Can) with 5.92%.
In the 2019 European elections, HDZ won 22.72% of the votes, followed by SDP with 18.71%.
Croatia will hold 12 of the 720 seats in the new European Parliament. While DIP did not provide figures on the allocation by parties on Monday morning, local daily Jutarnji List reported that HDZ will have six seats, SDP and its partners will have four seats, and each of DP and Mozemo will have one seat.
Croats voted for the European Parliament for the fourth time on Sunday, following the country's accession to the European Union on July 1, 2013.
The results of the Sunday vote reflected similar outcomes to the general election held in April, after which HDZ and its partners formed a coalition government with DP led by HDZ leader Andrej Plenkovic.
Some 3.7 million Croatian voters were eligible to choose among 300 candidates in Sunday's elections.