The agricultural transition to more resilient and efficient farming is transforming food production systems in many regions globally. An important element of this global transition is exhibited through technological developments in farming practices. Their implications on the rural livelihoods employed in agriculture, however, have not been analysed at a global level. Here, we quantify the number of agricultural labourers that will be needed in agriculture following this agrarian transition. We focus on the potential labour reserves by simulating two what-if scenarios of incremental and very fast transition of mechanisation development in food systems and compare them to a baseline resembling the current state of agricultural employment. Presently, agriculture requires 286 million full-time equivalent workers (AWU) to reach the 2011-2015 production volumes of 21 major agricultural products. An incremental mechanisation development decreases the labour requirements to 74 million AWU while a very fast transition in mechanisation further reduces requirements to 19 million AWU. Given the significant implications of agricultural mechanisation on global labour requirements, our analysis demonstrates the need for forthcoming policies to consider the viability of rural groups led to exit agriculture in order to ensure a meaningful transition for the smallholders globally.