Oscar's early liberal outlook and progressive ideas on such issues as fiscal policy, freedom of the press, and penal reform fortuitously coincided with a period of social, political, and industrial change. After his accession (March 8, 1844) he worked with the Riksdag (parliament) to further various reforms. Among these were the institution of equal rights of inheritance for men and women (1845), the abolition of the guild system (1846), and the enactment of the right of unmarried women to come of age at age 25 (1858).

Oscar broke with his father's pro-Russian foreign policy, and in 1855 Sweden promised to join the French and British side in the Crimean War. Sweden, however, never declared war on Russia and, as a result, managed to secure Russian promises not to fortify the Åland Islands. Oscar was also a firm believer in Skandinavism, the idea that there existed a great cultural bond between the Scandinavian countries—Denmark, Norway, and Sweden—and, accordingly, also good possibilities for closer relations between the three countries.