On 6 October 2006 Lars Leijonborg was made Minister for Education and Research in the Cabinet of Fredrik Reinfeldt.

On 16 October 2006, Leijonborg temporarily took over the responsibilities for Minister for Culture Cecilia Stegö Chilò, who resigned that day.

His successor as chairman, Minister for Schools Jan Björklund also took office as the new head of the Ministry of Education and Research.

Leijonborg remained in the cabinet, keeping his political assignments as a minister for higher education and research but resigned from the government on 11 June 2009.

Leijonborg is a member of the congregationalist Mission Covenant Church of Sweden (Swedish: Svenska Missionskyrkan).