His research intersects with sociology, psychology, political science, and communications. His current projects explore political challenges and innovations, including populism, polarization, and public participation. One stream of research explores the group processes and emotional underpinnings of political polarization and populism. Another examines why people are more likely to be motivated to form an accurate or reasoned political preference as opposed to align uncritically with political elites. Ársælsson's research also examines when workers promote civic values and social responsibility at their workplaces.

His teaching interests at Duke Kunshan include social psychology, political behavior, and public opinion formation. In his courses, he trains students to link theory, data, and methods. Ársælsson leads a Pedagogical Research and Practice lab at the Institute for Global Higher Education.

He has published research in academic journals including the American Journal of Sociology, Political Behavior, Public Opinion Quarterly, and Political Psychology. Previously, he worked as a consultant for public institutions, a team leader the Environment Agency of Iceland, and a radio producer/presenter. He also founded a think tank in Iceland focusing on democracy and sustainability.

He has a B.A. in philosophy, an M.A. in sociology, and a diploma in teaching from the University of Iceland, and a Ph.D. in sociology from the University of Wisconsin-Madison.