[7] Borzan got involved in politics in 1999 by joining Social Democratic Party of Croatia (SDP), because she "couldn't be a passive observer" since she was "dissatisfied with the level of democracy, tolerance, and justice in the country following the rule of President Franjo Tuđman".

[12] She is the main author of the Regulations in the European Parliament's Committee on Internal Market and Consumer Protection, which makes cross-border delivery more cost-effective for the EU citizens, and make it easier for small and medium-sized businesses to enter the wider market.

[13] On 25 September 2017, Europe's leading baby food brand Hipp Holding announced that it would relaunch one of its products after jars sold in Eastern Europe were found to contain a lower proportion of vegetables and an omega-3 source compared with the identically branded product sold in the Western Europe, following the publication of the results of the research initiated by Borzan herself, and supervised by the Croatian Food Agency.

[15][16] She later pushed for EU legislation on the issue and the banning of dual quality of products in the Unfair Commercial Practices Directive.

In 2018, she played an important role in the legislative process related to the relocation of the Agency from London to Amsterdam.

[22] In 2018, The Parliament Magazine presented Borzan with "The Women’s Rights and Gender Equality Award".

[23] Borzan was born as Biljana Čupurdija (Serbian Cyrillic: Биљана Чупурдија) in a Croatian Serb family.

[24][2] Her father Jovo was an active member of the League of Communists of Croatia, and her mother Rosa worked in the State Security Service.

[3] In her free time, she loves to paint, sing, read, and sew the clothes she wears.