Sinkamba founded Citizens for a Better Environment in 1997 due to the social and environmental risks of unregulated copper mining, particularly to the people living near mines.
He helped fight for sustainable relocation of communities whose houses were affected by mining activities on the Copperbelt. This includes the relocation of Ming'omba and Kawama communities by Konkola Copper Mines (KCM) in Chililabombwe. This relocation was done between 2000 and 2003 and involved of over 100 houses. He also helped relocation of over 100 households in Mufulira affected by cracking of houses due to historical mining activities.
He also helped set up a multi-million dollars Environmental Protection Fund for the mining sector in Zambia into which mining companies are obliged to contribute to cover their environmental liabilities. The objectives of the fund are to ensure that mining companies have sufficient resources to implement their environmental management plans, and also to provide a guarantee to government not to use public funds in the event that the mining company fails to rehabilitate its site.
When Anglo American Corporation pulled out Zambia in 2002, Sinkamba, through what he called the "Copperbelt Manifesto" rallied civil society groups across the globe to pressurize Anglo sustainably mitigate its environmental and social liabilities on the Copperbelt. This initiative led to Anglo setting up the Copperbelt Development Foundation and donating over 40% of shares in KCM to the foundation.
He has also negotiated, on behalf of government, World Bank support to mitigate historical environmental and social issues on the Copperbelt as well as the lead poisoning problem in Kabwe. Between 2002 and 2017 the World Bank and other have committed in excess of $100 million to address historical environmental and social problems on the Copperbelt and Kabwe.
Sinkamba started politics in mainstream politics in 1990 as a youth activist under the Movement for Multiparty Democracy (MMD). In 1991, he became the Deputy Secretary General for the National Democratic Alliance (NADA) and later the Secretary General of the National Conservative Party (NCP). He served on the Mwanakatwe Constitutional Review Commission to draft the Constitution of the Country from 1993 to 1994. He later founded the Green Party in 2013. As a candidate for the newly formed (2013) Green Party of Zambia in the 2015 presidential election, Sinkamba earned 1,410 votes. He later contested presidential election in 2016 earning 4,515 2016 Zambian general election#President.
Sinkamba has proposed that Zambia legalize marijuana in order to diversity its economy.
- "Green Party of Zambia". Retrieved 9 December 2015.
- "Meet A Playboy Entrepreneur Who Went From Making Millions To Making an Impact". Forbes. Retrieved 9 December 2015.
- "Can Zambia save its environment with marijuana?". The Guardian. Retrieved 9 December 2015.