The Gaia hypothesis, which proposed Earth as a planetary superorganism, was dismissed due to perceived conflicts with natural selection and unclear mechanisms for its emergence. Here, we address these issues by developing the <em>Organic Gaia Theory</em>. This theory holds that the emergence, sustainability and evolution of Gaia as superorganism can be explained by three observable and interrelated hypotheses: 1) the tendency of dissipative systems to follow<em> Thermodynamic Maximization Principles</em> by evolving toward structures of higher material and energy use until some local limit is reached; 2) the tendency of complex dissipative systems to organize in <em>Prigogine trinomials</em>, i.e. to become functional parts of a larger structure with the emerging capacities to coordinate its functional parts and to adapt its environment to its benefit; and 3) the tendency of expansive and reproductive systems to overcome local limits to their growth and complexity through the formation of trinomials of Prigogine trinomials through the process of symbiotic cooperation and <em>organic symbiogenesis</em>. The interplay of these processes make the emergence of a super-organism at planetary scale (Gaia) not only possible but probable. Aligning Gaia with thermodynamic and biological principles the theory implies a potential paradigm shift in biological and Earth system sciences.