He was born in Vancouver to Stefan and Marta Heyman, a Polish-Jewish couple who escaped occupied Poland during the Second World War by way of Japan with the help of Chiune Sugihara, the Japanese Empire vice-consul at Kaunas, Lithuania.

[9] He oversaw the financial and administrative health of the organization as well as being Sierra Club’s primary public spokesperson on issues regarding energy, mining, conservation of species and habitat, climate change, environmental assessment, forest management and sustainable economic alternatives.

Heyman faced high-profile Vancouver city councillor Geoff Meggs in the nomination contest to become the BC NDP candidate for Vancouver-Fairview in the 2013 provincial election.

After winning re-election in the 2017 provincial election,[16] Heyman was appointed the Minister of Environment and Climate Change Strategy in the newly formed NDP minority government on July 18, 2017.

[18] In the new cabinet announced by Premier David Eby on December 7, 2022, he retained the post of Minister of Environment and Climate Change Strategy, while the separate TransLink portfolio was abolished.