<p>Microbiomes of soil, plants, and the animal gut are pivotal for key life processes such as nutrient cycling, stress resilience, and immunity. While studies have hinted at a shared microbial reservoir connecting these environments, compelling evidence of a soil-plant-gut microbiome axis is scarce. This perspective explores the potential continuum and diversification of microbes along this axis, highlighting specific microorganisms capable of moving from soil to plants to the human gut. A conceptual framework is proposed to better understand the mechanisms driving interactions among these microbiomes. We also examine how soil, plant, and gut microbiomes may co-evolve and influence one another through reciprocal effects. We consider external environmental factors that could strengthen their interconnections, potentially creating beneficial feedback loops that impact ecosystem and human health.</p>