During the 2019 European Parliament Elections, Síona Cahill campaigned tirelessly to encourage more student engagement and voter registration, by launching the #GenerationVote campaign, and created a 'student manifesto' for MEP candidates on climate change and education.

Additionally, Cahill launched and created the #GetRegd National Voter Registration campaign to register students to vote, and during the 2018 Irish Referendum, she coordinated colleges in registering over 27,000 students to vote. Cahill also organized a 'National Voter Registration day' 4 years in a row, incorporating other youth sector bodies in Ireland. Moreover, she has delivered workshops and seminars on women and leadership, campaigning, and activism.

Cahill set up the USI 'Women Lead Project' in 2016, directly training over 120 women and self-defining women in capacity-building for leadership roles and elected positions in the students unions, student societies, and community organizations, resulting in a significant increase of young female student union candidates. Furthermore, she has been the main contributor to the USI's 'Student response to the British Exit of the European Union.' Cahill has empowered students, in particular, female students, to become part of the conversation around Europe, Brexit, and social issues affecting Ireland and the rest of the EU.