In 1827 Arwidsson undertook a research trip to Finland, but was immediately deported back to Sweden by the authorities. This experience led to a further radicalisation of his political work, and as a result he participated in several public debates in Sweden, in each of which he represented the situation in Finland in a dark light, but at the same time tried to portray the Finnish-national identity positively. Apart from his political work, Arwidsson also produced several historical research works. In 1843 he was appointed director of the royal library. In the same year he was allowed to travel to Finland, but he only took advantage of this possibility in 1858, when he undertook a round trip through Finland. During this journey Arwidsson caught pneumonia, and died on 21 June in Viipuri. He was buried in his childhood home town of Laukaa. The following verses written by Elias Lönnrot were later carved onto his gravestone: