He worked closely with Nelson Mandela during the settlement talks, served as negotiator for the ANC, and participated in drafting the South African Constitution.

Valli played an important role in the campaign against the apartheid-era South African Indian Council.

[13] Valli contributed to the creation of a progressive non-racial network of democrats across the country, through mass-based residents and civic organisations.

He was a founding member of the United Democratic Front (South Africa)(UDF) 1983 and served on its National Committee.

The Internal Leadership Core, under the chairpersonship of Walter Sisulu was responsible for establishing and managing the legal organisational structure of the ANC.

[33] He represented South Africa at various sessions of the UN Convention on Climate Change and was appointed as the Global facilitator for the final negotiations on the Kyoto Protocol at the seventh Conference of the Parties (COP7) held in Marrakech in 2001.

[34] He served as the Chairperson of the UN Commission on Sustainable Development (2002-2003) [8] • President of the IUCN (International Union for the Conservation of Nature).

He was elected the global President of IUCN by an overwhelming majority of 432 votes to 199 at the 3rd World Conservation Congress in Bangkok in November 2004.

The report foresees a durable legal agreement that sets binding commitments for all parties, holds countries accountable, and works to progressively strengthen global ambition.

The report was prepared by Valli and Harald Dovland of Norway, co-chairs of a year-long dialogue among negotiators from China, the United States and 20 other European, Asian, Latin American and African countries.

The report draws on nearly 100 hours of frank discussions among negotiators, who participated in their personal capacities and met eight times from March 2014 through May 2015.” • Member of the CCICED (China Council for International Co-operation on Environment and Development) from 2008 to 2012.

[35] • Chairman of UN High Level Panel on the CDM (Clean Development Mechanism) Policy Dialogue in 2012.

[40] • Member of the Steering Committee of the Tokyo based International Cool Earth Forum[41] • Deputy Chairperson and Head of the Presidential Climate Commission (PCC) (2020-2024)[42] The PCC is composed of representatives of trade unions, environment NGO's, business and the government.

Valli describes the act as "the single biggest improvement to South African democracy since the adoption of the Constitution in 1996”.