In 2000 Solheim left Norwegian politics to take up an appointment as a special adviser in the Ministry of Foreign Affairs working as a participant in the Norwegian delegation that unsuccessfully attempted to resolve the Sri Lankan Civil War before the outbreak of Eelam War IV.

After leaving the government in 2012, he returned to his previous position as a special adviser in the Ministry of Foreign Affairs, and from 2013 to 2016 Solheim was chair of the OECD Development Assistance Committee in Paris.

In 1987, he became leader of the Socialist Left Party and rose quickly to become a popular figure in Norwegian politics.

Through the 1990s Solheim became one of the most prominent figures in Norwegian politics, and lead his party through a period of rising popularity.

In later years he has received criticism from some older party colleagues for moderating his views on the European Union and becoming a supporter of Norway's membership in NATO.

[8] From the spring of 2000 he was granted a leave of absence from parliament to serve as special advisor to the Norwegian Ministry of Foreign Affairs in Sri Lanka.

After meeting with the officials, Solheim told journalists in Colombo, "Everyone is worried with the present deteriorating security situation.

[9] Solheim announced on 12 September 2006 that the Government of Sri Lanka and the Tamil Tigers had agreed to hold "unconditional peace talks" in October in Oslo.

[10] Solheim told BBC News officials that "Both parties have expressed willingness to come back to the table.

Officials from the European Union, Japan, Norway and the United States, meeting in Brussels to discuss the conflict, released a statement in support of the peace talks.

[14] His attempts of peacemaking were in the end unsuccessful, with the Asian Tribune concluding that "his handling relationship with Sri Lanka" was an "utter failure".

[16] In an interview with journalists Easwaran Rutnam and Jamila Najmuddin, the Norwegian Minister of Environment, who has been often labelled in Sri Lanka as being pro-LTTE, said that the recent Wikileaks reports on him proved that he was not biased towards one party.

Solheim also rejected the idea of a separate State in Sri Lanka and urged the Tamil Diaspora to seek dialogue and work through democratic means to achieve their goals.

also stating that "Unfortunately, similar allegations based on the very same source, have lately also been published and broadcast by other parts of the Sri Lankan media.

"[21] "Norwegians Against Terrorism" is a one-man band led by convicted murderer Falk Rune Rovik.

This practice was defended by Erik Solheim, who stated that Norway had a long tradition of helping people at risk.

[26] Deutsche Welle editorialized that "his actions paint a questionable picture of a corrupt politician using a position of privilege to his own advantage.

[33] On 20 November 2018, United Nations Secretary-General António Guterres accepted Solheim's resignation, after asking him to step down.