Long an advocate of voluntary euthanasia legalisation, he ended his own life in Switzerland via physician-assisted suicide at age 104.

He underwent a medical examination for the Royal Navy, but as soon his boss heard of this he refused to release any of his researchers, claiming they were "much more important to the world of agriculture than the war effort".

[7] Over the course of his career Goodall supervised four doctoral and ten masters students, and even into retirement served on the editorial boards of several scientific journals, including Vegetatio and Annual Review of Ecology and Systematics.

Botanist David Ashton credits him with providing "enormous stimulus" to research in nutritional physiology following World War II.

[8] With a series of papers in the 1950s and 1960s titled "Objective Methods for the Classification of Vegetation" he helped turn plant ecology from a descriptive, subjective science into one more quantitative and repeatable.

[10][11] In the late 1960s he co-founded and was director of the Desert Biome project of the International Biological Program, where he organised simulation modelling of processes such as desertification and overgrazing on arid lands.

His daughter warned that the move would have a dramatic impact on his sense of independence and mental well-being and stated "I do not know whether he would survive it".

[14] This decision caused an uproar, and the university compromised by relocating him to a new office at its Mount Lawley campus, significantly closer to his home.

[27] When asked why he thought he had managed to reach such a great age, he noted that "genetics helps" but urged "to keep alive, keep active.

[28][29] Goodall advocated for the legalisation of voluntary euthanasia, being a member of assisted dying advocacy group Exit International for over twenty years.

[32] The business class flight tickets to Europe, for himself and his helpers, were financed by crowdfunding via the website GoFundMe, where 376 donors exceeded the target of A$20,000.

"[34] Goodall travelled first to France to visit family, and then to Liestal, Switzerland, where two doctors cleared him to proceed with his assisted suicide,[35] although he was not terminally ill.

In Switzerland, Exit International organised a press conference during which Goodall answered journalists' questions and sang the first few lines of the fourth movement of Beethoven's Ninth Symphony, based on Friedrich Schiller's poem Ode to Joy, in German.